fix (cloud) non-obvious error message ('handler not found') that occurs at the time of script loading

Author: vengrov

lib/server-code/model/descriptor.js

@@ -46,6 +46,10 @@ class ServerCodeModelDescriptor {
     model.definitions.setExplicitly(this.definitions);
     model.loadFiles(this.codePath, this.typesFiles.concat([file]));
 
+    if (model.errors.length) {
+      throw new Error(`Error while loading [${model.errors[0].serverCodeFile}]. ${model.errors[0].message}`);
+    }
+    
     return model;
   }