use two fallbacks to get collection

Author: jankapunkt

lib/client/fileUpload.js

@@ -22,19 +22,26 @@ Template.afFileUpload.onCreated(function () {
     };
   }
 
+  // primary method: use dburles:mongo-collection-instances
   if (Mongo.Collection.get) {
     const mongoCollection = Mongo.Collection.get(this.data.atts.collection);
     this.collection = mongoCollection && mongoCollection.filesCollection;
-  } else {
-    // if newer than 2016 use _stores
-    // else use _mongo_livedata_collections
-    // see https://github.com/meteor/meteor/pull/5845
+  }
+
+  // 1. fallback using global scope
+  if (!this.collection) {
+    this.collection = global[this.data.atts.collection];
+  }
+
+  // 2. fallback using Meteor.connection / local collections
+  // if the Meteor release is newer than 2016 -> use _stores
+  // else use older _mongo_livedata_collections
+  // see https://github.com/meteor/meteor/pull/5845
+  if (!this.collection) {
     const storedCollection =  Meteor.connection._stores[this.data.atts.collection];
-    const liveDataCollection = storedCollection && storedCollection._getCollection
+    this.collection = (storedCollection && storedCollection._getCollection)
       ? storedCollection._getCollection().filesCollection
       : Meteor.connection._mongo_livedata_collections[this.data.atts.collection];
-    const globalCollection   = global[this.data.atts.collection];
-    this.collection = liveDataCollection || globalCollection;
   }
 
   if (!this.collection) {