Move up assertArray() check.

Passing a non-array was throwing an error about batching. The error
message provided by assertArray is more likely to help users isolate
their mistake.

Author: jamestalmage

src/firebase.js

@@ -248,14 +248,16 @@
               }
             }
           });
+
+          assertArray(array);
+
           var error   = batch(array.$$error, array);
           var resolve = batch(_resolveFn);
 
           var self = this;
           self.isDestroyed = false;
           self.getArray = function() { return array; };
 
-          assertArray(array);
           init();
         }
 

tests/unit/firebase.spec.js

@@ -478,7 +478,8 @@ describe('$firebase', function () {
       expect(function() {
         function fn() { return {}; }
         $firebase(new Firebase('Mock://').child('data'), {arrayFactory: fn}).$asArray();
-      }).toThrowError(Error);
+      }).toThrow(new Error('arrayFactory must return a valid array that passes ' +
+      'angular.isArray and Array.isArray, but received "[object Object]"'));
     });
 
     it('should contain data in ref() after load', function() {