I've been experimenting with threading and running bits of python from iTerm in MacOS yesterday. Today I opened iTerm and two windows opened, one with thick red lines inside it. I received a Warning message from MacOS:
A session ended very soon after starting. Check that the command in profile “Default” is correct.
I said OK, the window with the red closed immediately, and I quit iTerm.
Question: What is really happening here? I've never seen red lines appear in iTerm2 or a session close immediately upon starting. Is this just "one of those things" or could something be seriously wrong that needs attention?
I only have one profile, called default.
edit: after coaching in comments, I restarted iTerm2, same red lines. Engaged a second brain cell and realized I can move the error message out of the way, revealing the message in red in the iTerm2 window: