Error loading module when Array prototype is modified

[Sembiance]

The following code produces an error when loading css-tree:

"use strict";
Array.prototype.anything = function() { };
require("css-tree");

The error produced:

/tmp/node_modules/css-tree/lib/lexer/structure.js:112
                throw new Error('Wrong value in `' + name + '` structure definition');
                ^

Error: Wrong value in `CDC` structure definition
    at processStructure (/tmp/node_modules/css-tree/lib/lexer/structure.js:112:23)
    at getStructureFromConfig (/tmp/node_modules/css-tree/lib/lexer/structure.js:134:39)
    at Lexer (/tmp/node_modules/css-tree/lib/lexer/Lexer.js:125:35)
    at createSyntax (/tmp/node_modules/css-tree/lib/syntax/create.js:70:20)
    at Object.exports.create (/tmp/node_modules/css-tree/lib/syntax/create.js:81:12)
    at Object.<anonymous> (/tmp/node_modules/css-tree/lib/syntax/index.js:14:38)
    at Module._compile (module.js:573:30)
    at Object.Module._extensions..js (module.js:584:10)
    at Module.load (module.js:507:32)
    at tryModuleLoad (module.js:470:12)

Some modules out there may add additional functions to the Array prototype and this then prevents the css-tree module from being loaded.

Can be fixed by adding this line to css-tree/lib/lexer/structure.js on line 102:

if(!structure.hasOwnProperty(key)) { continue; }

Not sure exactly what the structure.js code is doing here, so not sure if the proposed fix is safe for your code, but my hunch says it is.

[lahmatiy]

Nice finding! Thank you for the report.
Fixed.