Do not check window object for URL parameters if window is not defined (#155)

* if the program is ran under nodejs, do not attempt to get URL properties (checking for window will break

* Merge branch 'master' into master

* formatting

* fixed lint error

* Merge branch 'master' into master

Author: arthurjdam

src/environment.ts

@@ -139,6 +139,10 @@ const DEEPLEARNJS_FLAGS_PREFIX = 'dljsflags';
 function getFeaturesFromURL(): Features {
   const features: Features = {};
 
+  if(typeof window === 'undefined') {
+    return features;
+  }
+
   const urlParams = util.getQueryParams(window.location.search);
   if (DEEPLEARNJS_FLAGS_PREFIX in urlParams) {
     const urlFlags: {[key: string]: string} = {};