gitsign failing when integrated with Google oAuth2

[rafaeltuelho]

When signing a git commit I get the following error:

git commit -S -m "Test of a signed commit"

Your browser will now be opened to:
https://accounts.google.com/o/oauth2/v2/auth?access_type=online&client_id=109....apps.googleusercontent.com&code_challenge=AJgmb...&code_challenge_method=S256&nonce=2iQd...&redirect_uri=http%3A%2F%2Flocalhost%3A59441%2Fauth%2Fcallback&response_type=code&scope=openid+email&state=2iQdUmXCZcLV3qeywd1ZWHxhjtd

error getting signer: oauth2: "invalid_request" "client_secret is missing."
failed to get identity: oauth2: "invalid_request" "client_secret is missing."
error: gpg failed to sign the data:
Error: failed to get identity: oauth2: "invalid_request" "client_secret is missing."

Here is my git local config for this test:

cat .git/config
[core]
	repositoryformatversion = 0
	filemode = true
	bare = false
	logallrefupdates = true
	ignorecase = true
	precomposeunicode = true
[remote "origin"]
	url = https://github.com/rafaeltuelho/code-sign-demo.git
	fetch = +refs/heads/*:refs/remotes/origin/*
[branch "main"]
	remote = origin
	merge = refs/heads/main
[commit]
	gpgsign = true
[tag]
	gpgsign = true
[gpg "x509"]
	program = gitsign
[gpg]
	format = x509
[gitsign]
	fulcio = https://fulcio-server-trusted-artifact-signer.apps.cluster.com
	rekor = https://rekor-server-trusted-artifact-signer.apps.cluster.com
	issuer = https://accounts.google.com
	clientID = 1091....apps.googleusercontent.com
	tokenProvider = interactive

What might I be missing? 🤔

I would appreciate it if you could point out anything here.