Gmail is not authorized — complete OAuth consent
The mailer tried to create a Gmail OAuth2 transport and found no gmailRefreshToken. Shorter sibling of the Admin-path assert message — same root cause at send time.
Why this happens
mode === "gmail" with client ID/secret present but authorization never completed (or token was cleared). Distinct from missing client ID/secret errors.
Diagnose and fix
1. Same fix as the Admin-path article: complete OAuth under Settings → Email.
2. Prefer Gmail XOAUTH2 checklist (scopes, Disconnect → Connect again).
3. Until authorized, switch temporarily to SMTP if you need mail urgently.
4. After connect, retry verification / password-reset / notification sends.