Object doesn't support this action - all of a sudden

Question

I'm running version 1.7.5 and for some incomprehensible reason, all of a sudden I'm getting syntax errors (none of my stylesheets have changed since it was working) and I'm including the .js file in the same way):

Object doesn't support this action

I've traced the error to this curious fragment (line 7880):

new(less.Parser)(env).parse(data, function (e, root) {
    if (e) { return callback(e, null, null, sheet); }
    try {
        callback(e, root, data, sheet, webInfo, path);
    } catch (e) {
        callback(e, null, null, sheet);
    }
}, {modifyVars: modifyVars, globalVars: less.globalVars});

...in the loadStyleSheet function. I don't understand that syntax, in fact, and trying it at the console I get the same error message:

new(less.Parser) # fails
new(less.Parser)(env) # fails
typeof less.Parser # yields "function"

what is going on here?

description: "Object doesn't support this action" message: "Object doesn't support this action" number: -2146827843 stack: "TypeError: Object doesn't support this action\n at Parser (http://localhost:53109/Scripts/System/less-1.7.5.js:360:5)\n at Anonymous function (http://localhost:53109/Scripts/System/less-1.7.5.js:7880:13)\n at Anonymous function (http://localhost:53109/Scripts/System/less-1.7.5.js:7838:13)\n at handleResponse (http://localhost:53109/Scripts/System/less-1.7.5.js:7763:13)\n at doXHR (http://localhost:53109/Scripts/System/less-1.7.5.js:7783:9)\n
at loadFile (http://localhost:53109/Scripts/System/less-1.7.5.js:7832:5)\n at loadStyleSheet (http://localhost:53109/Scripts/System/less-1.7.5.js:7856:5)\n at loadStyleSheets (http://localhost:53109/Scripts/System/less-1.7.5.js:7896:9)\n at less.refresh (http://localhost:53109/Scripts/System/less-1.7.5.js:7973:5)\n at Anonymous function (http://localhost:53109/Scripts/System/less-1.7.5.js:7999:1)"

* Update I *

so the syntax seems to be ok. I can do:

new(function() {})('x')

so given that less.Parser is a function the code should work... but it doesn't. here's what I get if I look at less.Parser:

function Parser(env) {
    var input,       // LeSS input string
        i,           // current index in `input`
        j,           // current chunk
        saveStack = [],   // holds state for backtracking
        furthest,    // furthest index the par
    [Methods]: {...}
    __proto__: 
function() {
    [native code]
}

    arguments: null
    caller: null
    length: 1
    prototype: {...}

does anything look amiss?

* Update II *

realising 1.7.5 is far behind the current, I upgraded to 2.5.0 (right off the CDN) but now it breaks elsewhere (line 2440):

if (typeof Object.create === 'undefined') {
    var F = function () {};
    F.prototype = Error.prototype;
    LessError.prototype = new F();
} else {
    LessError.prototype = Object.create(Error.prototype); # breaks here
}

with the error:

Object.create: argument is not an Object and is not null

and if I look at Error.prototype I get undefined... grr...

Answer 1

after a bit of wailing and gnashing of teeth I figured it out. one of my scripts was setting:

var Error = {};

lesson learned: beware with your variable names! it would have been nice if the compiler had complained about it.