Quick fix to prevent duplicate child event listeners on Java database module

Author: chrisbianca

android/src/main/java/io/fullstack/firestack/FirestackDatabase.java

@@ -10,6 +10,7 @@
 
 import com.facebook.react.bridge.Callback;
 import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.WritableArray;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.bridge.ReactMethod;
@@ -79,11 +80,9 @@ public void onCancelled(DatabaseError error) {
           self.handleDatabaseError(name, mPath, error);
         }
       };
+      Query ref = this.getDatabaseQueryAtPathAndModifiers(modifiersArray);
+      ref.addChildEventListener(mEventListener);
     }
-
-    Query ref = this.getDatabaseQueryAtPathAndModifiers(modifiersArray);
-    ref.addChildEventListener(mEventListener);
-    //this.setListeningTo(mPath, modifiersString, name);
   }
 
   public void addValueEventListener(final String name, final ReadableArray modifiersArray, final String modifiersString) {