feat(error): Decouple public error codes, modularize error files, and enable declaration merging

.eslintrc.js

@@ -71,6 +71,15 @@ module.exports = {
         "selector": "variable",
         "format": ["camelCase", "UPPER_CASE"]
       },
+      {
+        "selector": "variable",
+        "modifiers": ["const"],
+        "format": ["PascalCase", "camelCase", "UPPER_CASE"],
+        "filter": {
+          "regex": "ErrorCode$", // Matches only if it ends exactly with ErrorCode
+          "match": true,
+        },
+      },
       {
         "selector": "parameter",
         "format": ["camelCase"],

etc/firebase-admin.app-check.api.md

@@ -17,7 +17,20 @@ export class AppCheck {
 }
 
 // @public
-export type AppCheckErrorCode = 'aborted' | 'invalid-argument' | 'invalid-credential' | 'internal-error' | 'permission-denied' | 'unauthenticated' | 'not-found' | 'app-check-token-expired' | 'unknown-error';
+export const AppCheckErrorCode: {
+    readonly ABORTED: "aborted";
+    readonly INVALID_ARGUMENT: "invalid-argument";
+    readonly INVALID_CREDENTIAL: "invalid-credential";
+    readonly INTERNAL: "internal-error";
+    readonly PERMISSION_DENIED: "permission-denied";
+    readonly UNAUTHENTICATED: "unauthenticated";
+    readonly NOT_FOUND: "not-found";
+    readonly APP_CHECK_TOKEN_EXPIRED: "app-check-token-expired";
+    readonly UNKNOWN: "unknown-error";
+};
+
+// @public
+export type AppCheckErrorCode = typeof AppCheckErrorCode[keyof typeof AppCheckErrorCode];
 
 // @public
 export interface AppCheckToken {

etc/firebase-admin.app.api.md

@@ -13,30 +13,22 @@ export interface App {
 }
 
 // @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;
-}
+export const AppErrorCode: {
+    readonly APP_DELETED: "app-deleted";
+    readonly DUPLICATE_APP: "duplicate-app";
+    readonly INVALID_ARGUMENT: "invalid-argument";
+    readonly INTERNAL_ERROR: "internal-error";
+    readonly INVALID_APP_NAME: "invalid-app-name";
+    readonly INVALID_APP_OPTIONS: "invalid-app-options";
+    readonly INVALID_CREDENTIAL: "invalid-credential";
+    readonly NETWORK_ERROR: "network-error";
+    readonly NETWORK_TIMEOUT: "network-timeout";
+    readonly NO_APP: "no-app";
+    readonly UNABLE_TO_PARSE_RESPONSE: "unable-to-parse-response";
+};
+
+// @public
+export type AppErrorCode = typeof AppErrorCode[keyof typeof AppErrorCode];
 
 // @public
 export function applicationDefault(httpAgent?: Agent): Credential;