Description:
When opening a cleartext-signed message that had another cleartext-signed message quoted in it, it triggers an error saying:
And if we look at the higher hirarchy of the cleartext-signed message by clicking the "show original message", we can see part that is within the error message block and the leftover signature that was left behind on Gmail message thread:
Email thread that had the UI issue: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzQfBGjNHltkmvDsgmgCBhbWJPlb