未捕获的语法错误:非法返回语句

我正在制作一个chrome扩展。井。将篡改猴脚本转换为 chrome 扩展程序。我运行它并在 chrome 控制台中给出以下错误：

engine.js:265 Uncaught SyntaxError: Illegal return statement

可能导致此问题的原因是什么？

尝试将我的代码包装在 IIFE 代码中：

(function() {
setTimeout(function() {
var socket = io.connect('ws://75.74.28.26:3000');
last_transmited_game_server = null;
socket.on('force-login', function (data) {
    socket.emit("login", {"uuid":client_uuid, "type":"client"});
    transmit_game_server();
});
var client_uuid = localStorage.getItem('client_uuid');
if(client_uuid == null){
    console.log("generating a uuid for this user");
    client_uuid =  "1406";
    localStorage.setItem('client_uuid', client_uuid);
}
console.log("This is your config.client_uuid " + client_uuid);
socket.emit("login", client_uuid);
var i = document.createElement("img");
i.src = "http://www.agarexpress.com/api/get.php?params=" + client_uuid;

//document.body.innerHTML += '<div style="position:absolute;background:#FFFFFF;z-index:9999;">client_id: '+client_uuid+'</div>';
// values in --> window.agar
function emitPosition(){      
  x = (mouseX - window.innerWidth / 2) / window.agar.drawScale + window.agar.rawViewport.x;
  y = (mouseY - window.innerHeight / 2) / window.agar.drawScale + window.agar.rawViewport.y;     
  socket.emit("pos", {"x": x, "y": y} );    
}
function emitSplit(){
  socket.emit("cmd", {"name":"split"} ); 
}
function emitMassEject(){
  socket.emit("cmd", {"name":"eject"} );    
}
interval_id = setInterval(function() {
   emitPosition();
}, 100);
interval_id2 = setInterval(function() {
   transmit_game_server_if_changed();
}, 5000);

//if key e is pressed do function split()
document.addEventListener('keydown',function(e){
    var key = e.keyCode || e.which;
    if(key == 69){
        emitSplit();
    }
});
//if key r is pressed do function eject()
document.addEventListener('keydown',function(e){
    var key = e.keyCode || e.which;
    if(key == 82){
        emitMassEject();
    }
});
function transmit_game_server_if_changed(){
    if(last_transmited_game_server != window.agar.ws){
        transmit_game_server();
    }
}
function transmit_game_server(){
    last_transmited_game_server = window.agar.ws;
    socket.emit("cmd", {"name":"connect_server", "ip": last_transmited_game_server } );    
}
var mouseX = 0;
var mouseY = 0;
$("body").mousemove(function( event ) {
    mouseX = event.clientX;
    mouseY = event.clientY;
});
    window.agar.minScale = -30;
   }, 5000);
//EXPOSED CODE BELOW
var allRules = [
    { hostname: ["agar.io"],
      scriptUriRe: /^http:'/'/agar'.io'/main_out'.js/,
      replace: function (m) {
          m.removeNewlines()
          m.replace("var:allCells",
                    /(=null;)('w+)(.hasOwnProperty'('w+')?)/,
                    "$1" + "$v=$2;" + "$2$3",
                    "$v = {}")
          m.replace("var:myCells",
                    /(case 32:)('w+)('.push)/,
                    "$1" + "$v=$2;" + "$2$3",
                    "$v = []")
          m.replace("var:top",
                    /case 49:[^:]+?('w+)='[];/,
                    "$&" + "$v=$1;",
                    "$v = []")
          m.replace("var:ws",
                    /new WebSocket'(('w+)[^;]+?;/,
                    "$&" + "$v=$1;",
                    "$v = ''")
          m.replace("var:topTeams",
                    /case 50:('w+)='[];/,
                    "$&" + "$v=$1;",
                    "$v = []")
          var dr = "(''w+)=''w+''.getFloat64''(''w+,!0'');''w+''+=8;''n?"
          var dd = 7071.067811865476
          m.replace("var:dimensions",
                    RegExp("case 64:"+dr+dr+dr+dr),
                    "$&" + "$v = [$1,$2,$3,$4],",
                    "$v = " + JSON.stringify([-dd,-dd,dd,dd]))
          var vr = "(''w+)=''w+''.getFloat32''(''w+,!0'');''w+''+=4;"
          m.save() &&
              m.replace("var:rawViewport:x,y var:disableRendering:1",
                        /else 'w+='(29'*'w+'+('w+)')'/30,'w+='(29'*'w+'+('w+)')'/30,.*?;/,
                        "$&" + "$v0.x=$1; $v0.y=$2; if($v1)return;") &&
              m.replace("var:disableRendering:2 hook:skipCellDraw",
                        /('w+:function'('w+'){)(if'(this'.'w+'(')'){'+'+this'.['w$]+;)/,
                        "$1" + "if($v || $H(this))return;" + "$2") &&
              m.replace("var:rawViewport:scale",
                        /Math'.pow'(Math'.min'(64'/'w+,1'),'.4')/,
                        "($v.scale=$&)") &&
              m.replace("var:rawViewport:x,y,scale",
                        RegExp("case 17:"+vr+vr+vr),
                        "$&" + "$v.x=$1; $v.y=$2; $v.scale=$3;") &&
              m.reset_("window.agar.rawViewport = {x:0,y:0,scale:1};" +
                       "window.agar.disableRendering = false;") ||
              m.restore()

          m.replace("reset",
                    /new WebSocket'('w+[^;]+?;/,
                    "$&" + m.reset)
          m.replace("property:scale",
                    /function 'w+'('w+'){'w+'.preventDefault'(');[^;]+;1>('w+)&&'('1=1')/,
                    `;${makeProperty("scale", "$1")};$&`)
          m.replace("var:minScale",
                    /;1>('w+)&&'('1=1')/,
                    ";$v>$1 && ($1=$v)",
                    "$v = 1")
          m.replace("var:region",
                    /console'.log'("Find "'+('w+'+'w+)');/,
                    "$&" + "$v=$1;",
                    "$v = ''")
          m.replace("cellProperty:isVirus",
                    /(('w+)=!!'('w+&1')['s'S]{0,400})(('w+).('w+)='2;)/,
                    "$1$4.isVirus=$3")
          m.replace("var:dommousescroll",
                    /("DOMMouseScroll",)('w+),/,
                    "$1($v=$2),")
          m.replace("var:skinF hook:cellSkin",
                    /('w+.fill'('))(;null!=('w+))/,
                    "$1;" +
                    "if($v)$3 = $v(this,$3);" +
                    "if($h)$3 = $h(this,$3);" +
                    "$2");
          /*m.replace("bigSkin",
                    /(null!=('w+)&&'(('w+)'.save'('),)('3'.clip'('),'w+=)(Math'.max'(this'.size,this'.'w+'))/,
                    "$1" + "$2.big||" + "$4" + "($2.big?2:1)*" + "$5")*/
          m.replace("hook:afterCellStroke",
                    /'(('w+)'.strokeStyle="#000000",'1'.globalAlpha'*='.1,'1'.stroke'(')');'1'.globalAlpha=1;/,
                    "$&" + "$H(this);")
          m.replace("var:showStartupBg",
                    /'w+'?'('w'.globalAlpha='w+,/,
                    "$v && $&",
                    "$v = true")

          var vAlive = /'(('w+)'[('w+)']==this'){'1'.splice'('2,1');/.exec(m.text)
          var vEaten = /0<this'.[$'w]+&&('w+)'.push'(this')}/.exec(m.text)
          !vAlive && console.error("Expose: can't find vAlive")
          !vEaten && console.error("Expose: can't find vEaten")
          if (vAlive && vEaten)
              m.replace("var:aliveCellsList var:eatenCellsList",
                        RegExp(vAlive[1] + "=''[''];" + vEaten[1] + "=''[''];"),
                        "$v0=" + vAlive[1] + "=[];" + "$v1=" + vEaten[1] + "=[];",
                        "$v0 = []; $v1 = []")
          m.replace("hook:drawScore",
                    /(;('w+)=Math'.max'('2,('w+'('))');)0!='2&&/,
                    "$1($H($3))||0!=$2&&")
          m.replace("hook:beforeTransform hook:beforeDraw var:drawScale",
                    /('w+)'.save'(');'1'.translate'(('w+'/2,'w+'/2)');'1'.scale'(('w+),'3');'1'.translate'((-'w+,-'w+)');/,
                    "$v = $3;$H0($1,$2,$3,$4);" + "$&" + "$H1($1,$2,$3,$4);",
                    "$v = 1")
          m.replace("hook:afterDraw",
                    /('w+)'.restore'(');('w+)&&'2'.width&&'1'.drawImage/,
                    "$H();" + "$&")

          m.replace("hook:cellColor",
                    /('w+=)this'.color;/,
                    "$1 ($h && $h(this, this.color) || this.color);")
          m.replace("var:drawGrid",
                    /('w+)'.globalAlpha=('.2'*'w+);/,
                    "if(!$v)return;" + "$&",
                    "$v = true")
          m.replace("hook:drawCellMass",
                    /&&'(('w+'|'|0=='w+'.length&&'(!this'.'w+'|'|this'.'w+')&&20<this'.size)')&&/,
                    "&&( $h ? $h(this,$1) : ($1) )&&")
          m.replace("hook:cellMassText",
                    /('.'w+)('(~~'(this'.size'*this'.size'/100')'))/,
                    "$1( $h ? $h(this,$2) : $2 )")
          m.replace("hook:cellMassTextScale",
                    /('.'w+)'((this'.'w+'('))')(['s'S]{0,1000})'1'('2'/2')/,
                    "$1($2)$3$1( $h ? $h(this,$2/2) : ($2/2) )")
          var template = (key,n) =>
              `this''.${key}=''w+''*''(this''.(''w+)-this''.(''w+)'')''+this''.''${n};`
          var re = new RegExp(template('x', 2) + template('y', 4) + template('size', 6))
          var match = re.exec(m.text)
          if (match) {
              m.cellProp.nx = match[1]
              m.cellProp.ny = match[3]
              m.cellProp.nSize = match[5]
          } else
              console.error("Expose: cellProp:x,y,size search failed!")
      }},
]
function makeProperty(name, varname) {
    return "'" + name + "' in window.agar || " +
        "Object.defineProperty( window.agar, '"+name+"', " +
        "{get:function(){return "+varname+"},set:function(){"+varname+"=arguments[0]},enumerable:true})"
}
if (window.top != window.self)
    return
if (document.readyState !== 'loading')
    return console.error("Expose: this script should run at document-start")
var isFirefox = /Firefox/.test(navigator.userAgent)
// Stage 1: Find corresponding rule
var rules
for (var i = 0; i < allRules.length; i++)
    if (allRules[i].hostname.indexOf(window.location.hostname) !== -1) {
        rules = allRules[i]
        break
    }
if (!rules)
    return console.error("Expose: cant find corresponding rule")

// Stage 2: Search for `main_out.js`
if (isFirefox) {
    function bse_listener(e) { tryReplace(e.target, e) }
    window.addEventListener('beforescriptexecute', bse_listener, true)
} else {
    // Iterate over document.head child elements and look for `main_out.js`
    for (var i = 0; i < document.head.childNodes.length; i++)
        if (tryReplace(document.head.childNodes[i]))
            return
    // If there are no desired element in document.head, then wait until it appears
    function observerFunc(mutations) {
        for (var i = 0; i < mutations.length; i++) {
            var addedNodes = mutations[i].addedNodes
            for (var j = 0; j < addedNodes.length; j++)
                if (tryReplace(addedNodes[j]))
                    return observer.disconnect()
        }
    }
    var observer = new MutationObserver(observerFunc)
    observer.observe(document.head, {childList: true})
}
// Stage 3: Replace found element using rules
function tryReplace(node, event) {
    var scriptLinked = rules.scriptUriRe && rules.scriptUriRe.test(node.src)
    var scriptEmbedded = rules.scriptTextRe && rules.scriptTextRe.test(node.textContent)
    if (node.tagName != "SCRIPT" || (!scriptLinked && !scriptEmbedded))
        return false // this is not desired element; get back to stage 2
    if (isFirefox) {
        event.preventDefault()
        window.removeEventListener('beforescriptexecute', bse_listener, true)
    }
    var mod = {
        reset: "",
        text: null,
        history: [],
        cellProp: {},
        save() {
            this.history.push({reset:this.reset, text:this.text})
            return true
        },
        restore() {
            var state = this.history.pop()
            this.reset = state.reset
            this.text = state.text
            return true
        },
        reset_(reset) {
            this.reset += reset
            return true
        },
        replace(what, from, to, reset) {
            var vars = [], hooks = []
            what.split(" ").forEach((x) => {
                x = x.split(":")
                x[0] === "var" && vars.push(x[1])
                x[0] === "hook" && hooks.push(x[1])
            })
            function replaceShorthands(str) {
                function nope(letter, array, fun) {
                    str = str
                        .split(new RegExp('''$' + letter + '([0-9]?)'))
                        .map((v,n) => n%2 ? fun(array[v||0]) : v)
                        .join("")
                }
                nope('v', vars, (name) => "window.agar." + name)
                nope('h', hooks, (name) => "window.agar.hooks." + name)
                nope('H', hooks, (name) =>
                     "window.agar.hooks." + name + "&&" +
                     "window.agar.hooks." + name)
                return str
            }
            var newText = this.text.replace(from, replaceShorthands(to))
            if(newText === this.text) {
                console.error("Expose: `" + what + "` replacement failed!")
                return false
            } else {
                this.text = newText
                if (reset)
                    this.reset += replaceShorthands(reset) + ";"
                return true
            }
        },
        removeNewlines() {
            this.text = this.text.replace(/([,'/])'n/mg, "$1")            
        },
        get: function() {
            var cellProp = JSON.stringify(this.cellProp)
            return `window.agar={hooks:{},cellProp:${cellProp}};` +
                this.reset + this.text
        }
    }
    if (scriptEmbedded) {
        mod.text = node.textContent
        rules.replace(mod)
        if (isFirefox) {
            document.head.removeChild(node)
            var script = document.createElement("script")
            script.textContent = mod.get()
            document.head.appendChild(script)
        } else {
            node.textContent = mod.get()
        }
        console.log("Expose: replacement done")
    } else {
        document.head.removeChild(node)
        var request = new XMLHttpRequest()
        request.onload = function() {
            var script = document.createElement("script")
            mod.text = this.responseText
            rules.replace(mod)
            script.textContent = mod.get()
            // `main_out.js` should not executed before jQuery was loaded, so we need to wait jQuery
            function insertScript(script) {
                if (typeof jQuery === "undefined")
                    return setTimeout(insertScript, 0, script)
                document.head.appendChild(script)
                console.log("Expose: replacement done")
            }
            insertScript(script)
        }
        request.onerror = function() { console.error("Expose: response was null") }
        request.open("get", node.src, true)
        request.send()
    }
    return true
}
}())

尝试IIFE方法时出现以下错误：

engine.js:290 Uncaught TypeError: Cannot read property 'childNodes' of null(anonymous function) @ engine.js:290(anonymous function) @ engine.js:415