refactor: created custom error for a token already exists

src/controllers/token/index.ts

@@ -3,6 +3,7 @@ import { env } from "hono/adapter";
 import mapKeys from "lodash.mapkeys";
 
 import { Case, changeStringCase } from "~/libs/changeStringCase";
+import { TokenAlreadyExistsError } from "~/libs/errors/TokenAlreadyExists";
 import type { AdminSdkCredentials } from "~/libs/fcm/getGoogleAuthToken";
 import { verifyFcmToken } from "~/libs/fcm/verifyFcmToken";
 import { readEnvVariable } from "~/libs/readEnvVariable";
@@ -69,7 +70,7 @@ app.openapi(route, async (c) => {
 
     await saveToken(env(c, "workerd"), deviceId, token, username);
   } catch (error) {
-    if (error.message === "Token already exists in the database") {
+    if (error instanceof TokenAlreadyExistsError) {
       return c.json(ErrorResponse, 412);
     }