fix #848

lib/modules/core/app.js

@@ -116,10 +116,12 @@ export default class App {
    * @param props
    */
   extendApp(props: Object) {
-    if (!isObject(props))
+    if (!isObject(props)) {
       throw new Error(
         INTERNALS.STRINGS.ERROR_MISSING_ARG('Object', 'extendApp')
       );
+    }
+
     const keys = Object.keys(props);
 
     for (let i = 0, len = keys.length; i < len; i++) {
@@ -167,4 +169,13 @@ export default class App {
       });
     });
   }
+
+  /**
+   * toString returns the name of the app.
+   *
+   * @return {string}
+   */
+  toString() {
+    return this._name;
+  }
 }

lib/utils/apps.js

@@ -38,7 +38,8 @@ export default {
 
   /**
    *
-   * @param statics
+   * @param app
+   * @param namespace
    * @param InstanceClass
    * @return {function()}
    * @private
@@ -152,8 +153,9 @@ export default {
 
   /**
    *
+   * @param namespace
    * @param statics
-   * @param InstanceClass
+   * @param moduleName
    * @return {function(App=)}
    */
   moduleAndStatics<M: FirebaseModule, S: FirebaseStatics>(