Fix api extractor issues to expose error types (#2549)

Author: lahirumaramba

etc/firebase-admin.app.api.md

@@ -14,6 +14,32 @@ export interface App {
     options: AppOptions;
 }
 
+// @public
+export class AppErrorCodes {
+    // (undocumented)
+    static APP_DELETED: string;
+    // (undocumented)
+    static DUPLICATE_APP: string;
+    // (undocumented)
+    static INTERNAL_ERROR: string;
+    // (undocumented)
+    static INVALID_APP_NAME: string;
+    // (undocumented)
+    static INVALID_APP_OPTIONS: string;
+    // (undocumented)
+    static INVALID_ARGUMENT: string;
+    // (undocumented)
+    static INVALID_CREDENTIAL: string;
+    // (undocumented)
+    static NETWORK_ERROR: string;
+    // (undocumented)
+    static NETWORK_TIMEOUT: string;
+    // (undocumented)
+    static NO_APP: string;
+    // (undocumented)
+    static UNABLE_TO_PARSE_RESPONSE: string;
+}
+
 // @public
 export function applicationDefault(httpAgent?: Agent): Credential;
 
@@ -39,6 +65,12 @@ export interface Credential {
 // @public
 export function deleteApp(app: App): Promise<void>;
 
+// Warning: (ae-forgotten-export) The symbol "PrefixedFirebaseError" needs to be exported by the entry point index.d.ts
+//
+// @public
+export class FirebaseAppError extends PrefixedFirebaseError {
+}
+
 // @public
 export interface FirebaseArrayIndexError {
     error: FirebaseError;