Cannot deploy Firebase Functions using `initializeapp`

Question

Deployment fails if initializeApp is used (I can deploy by commenting out initializeApp). I want to use Firebase functionality, so I want to deploy successfully even if I use initializeApp.
I would be grateful if you could tell me what you can think of.

• command:

firebase deploy --only functions

• error:

"error":{"code":3,"message":"Function failed on loading user code. This is likely due to a bug in the user code. Error message: Error: please examine your function logs to see the error cause: https://cloud.google.com/functions/docs/monitoring/logging#viewing_logs. Additional troubleshooting documentation can be found at https://cloud.google.com/functions/docs/troubleshooting#logging. Please visit https://cloud.google.com/functions/docs/troubleshooting for in-depth troubleshooting documentation."}}
[debug] [2022-04-20T11:59:45.071Z] Got source token 4a2e343d-2d38-45bf-b356-dfbee943ac68 for region us-central1
[debug] [2022-04-20T11:59:45.080Z] Total Function Deployment time: 91338
[debug] [2022-04-20T11:59:45.080Z] 1 Functions Deployed
[debug] [2022-04-20T11:59:45.080Z] 1 Functions Errored
[debug] [2022-04-20T11:59:45.081Z] 0 Function Deployments Aborted
[debug] [2022-04-20T11:59:45.081Z] Average Function Deployment time: 91335
[info] 
[info] Functions deploy had errors with the following functions:
    api(us-central1)
[debug] [2022-04-20T11:59:45.084Z] Missing URI for HTTPS function in printTriggerUrls. This shouldn't happen
[info] i  functions: cleaning up build files... 
[debug] [2022-04-20T11:59:51.612Z] Error: Failed to update function api in region us-central1
    at /usr/local/lib/node_modules/firebase-tools/lib/deploy/functions/release/fabricator.js:38:11
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async Fabricator.updateV1Function (/usr/local/lib/node_modules/firebase-tools/lib/deploy/functions/release/fabricator.js:268:32)
    at async Fabricator.updateEndpoint (/usr/local/lib/node_modules/firebase-tools/lib/deploy/functions/release/fabricator.js:134:13)
    at async handle (/usr/local/lib/node_modules/firebase-tools/lib/deploy/functions/release/fabricator.js:75:17)
[error] 
[error] Error: There was an error deploying functions

• code:

import cors from 'cors';
import { https } from 'firebase-functions';
import { initializeApp, App } from 'firebase-admin/app';
import express, { Request, Response } from 'express';

const firebaseApp: App = initializeApp();

const app = express();

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.use(cors({ origin: true }));

app.post('/', (req: Request, res: Response) => {
  res.send(200);
});

const api = https.onRequest(app);
export { api };

• versions:

Node: 16.14.2  
firebase-tools: 10.6.0  
cors: 2.8.5  
express: 4.17.3  
firebase-admin: 10.0.2  
firebase-functions: 3.20.1 

When executed locally, a warning message is played, but the execution is successful.

{"severity":"WARNING","message":"Warning, FIREBASE_CONFIG and GCLOUD_PROJECT environment variables are missing. Initializing firebase-admin will fail"}