Some self-hosted GitLab instances (e.g. older versions without
expires_in configured in doorkeeper) omit expires_in from the
OAuth token response. Computing Date.now()/1000 + undefined
produced NaN, which Postgres rejected on the expires_at integer
column, crashing both the initial OAuth callback and the token
refresh flow with a 500.
Falls back to null when expires_in is absent, matching the
existing Gitea callback behavior.
Closes#4362
Mauricio Siu
fc5b8d03e5
