Moved querying of environment variable

This fixes issues when environment variable is not configured before importing the module... which can be true for I figure a lot of Webpack configuration generators/factories like [edge-builder](https://github.com/sebastian-software/edge-builder). It imports dependencies via ESM import and executes the `main` function afterwards to parse command line arguments, etc.

Author: swernerx

loader.js

@@ -13,7 +13,6 @@ var SingleEntryPlugin = require("webpack/lib/SingleEntryPlugin");
 var LimitChunkCountPlugin = require("webpack/lib/optimize/LimitChunkCountPlugin");
 
 var NS = fs.realpathSync(__dirname);
-var DEV = process.env.NODE_ENV === 'development'
 
 module.exports = function(source) {
 	return source;
@@ -133,7 +132,7 @@ module.exports.pitch = function(request) {
 					//
 					// All we need is a date that changes during dev, to trigger a reload since
 					// hashes generated based on the file contents are what trigger HMR.
-					if (DEV) {
+					if (process.env.NODE_ENV === 'development') {
 						resultSource += `
 if (module.hot) {
 	module.hot.accept();