make thenable only implement then & catch

Author: Feiyang1

packages/database-types/index.d.ts

@@ -134,7 +134,9 @@ export interface ServerValue {
   increment(delta: number): Object;
 }
 
-export interface ThenableReference extends Reference, Promise<Reference> {}
+export interface ThenableReference
+  extends Reference,
+    Pick<Promise<Reference>, 'then' | 'catch'> {}
 
 export function enableLogging(
   logger?: boolean | ((a: string) => any),

packages/firebase/index.d.ts

@@ -6902,7 +6902,7 @@ declare namespace firebase.database {
 
   interface ThenableReference
     extends firebase.database.Reference,
-      Promise<Reference> {}
+      Pick<Promise<Reference>, 'then' | 'catch'> {}
 
   /**
    * Logs debugging information to the console.