old_contents: /*
  	MIT License http://www.opensource.org/licenses/mit-license.php
  	Authors Simen Brekken @simenbrekken, Einar Löve @einarlove
  */
  
  "use strict";
  
  const DefinePlugin = require("./DefinePlugin");
  
  class EnvironmentPlugin {
  	constructor(keys) {
  		if(Array.isArray(keys)) {
  			this.keys = keys;
  			this.defaultValues = {};
  		} else if(keys && typeof keys === "object") {
  			this.keys = Object.keys(keys);
  			this.defaultValues = keys;
  		} else {
  			this.keys = Array.prototype.slice.call(arguments);
  			this.defaultValues = {};
  		}
  	}
  
  	apply(compiler) {
  		const definitions = this.keys.reduce((defs, key) => {
  			const value = process.env[key] || this.defaultValues[key];
  
  			if(value === undefined) {
  				compiler.plugin("this-compilation", compilation => {
  					const error = new Error(
  						`EnvironmentPlugin - ${key} environment variable is undefined.\n\n` +
  						`You can pass an object with default values to suppress this warning.\n` +
  						`See https://webpack.js.org/plugins/environment-plugin for example.`
  					);
  
  					error.name = "EnvVariableNotDefinedError";
  					compilation.warnings.push(error);
  				});
  			}
  
  			defs[`process.env.${key}`] = typeof value === "undefined" ? "undefined" : JSON.stringify(value);
  
  			return defs;
  		}, {});
  
  		compiler.apply(new DefinePlugin(definitions));
  	}
  }
  
  module.exports = EnvironmentPlugin;
  
new_contents: /*
  	MIT License http://www.opensource.org/licenses/mit-license.php
  	Authors Simen Brekken @simenbrekken, Einar Löve @einarlove
  */
  
  "use strict";
  
  const DefinePlugin = require("./DefinePlugin");
  
  class EnvironmentPlugin {
  	constructor(keys) {
  		if(Array.isArray(keys)) {
  			this.keys = keys;
  			this.defaultValues = {};
  		} else if(keys && typeof keys === "object") {
  			this.keys = Object.keys(keys);
  			this.defaultValues = keys;
  		} else {
  			this.keys = Array.prototype.slice.call(arguments);
  			this.defaultValues = {};
  		}
  	}
  
  	apply(compiler) {
  		const definitions = this.keys.reduce((defs, key) => {
  			const value = process.env[key] || this.defaultValues[key];
  
  			if(value === undefined) {
  				compiler.plugin("this-compilation", compilation => {
  					const error = new Error(
  						`EnvironmentPlugin - ${key} environment variable is undefined.\n\n` +
  						"You can pass an object with default values to suppress this warning.\n" +
  						"See https://webpack.js.org/plugins/environment-plugin for example."
  					);
  
  					error.name = "EnvVariableNotDefinedError";
  					compilation.warnings.push(error);
  				});
  			}
  
  			defs[`process.env.${key}`] = typeof value === "undefined" ? "undefined" : JSON.stringify(value);
  
  			return defs;
  		}, {});
  
  		compiler.apply(new DefinePlugin(definitions));
  	}
  }
  
  module.exports = EnvironmentPlugin;
  
subject: Use double quotes