This was something I was planning to look at as a followup PR #12247. In the same way that AdaptDispatch and ConGetSet are designed to throw exceptions for error handling, the equivalent Terminal classes TerminalDispatch and ITerminalApi should be doing the same thing. That way exceptions like this would be caught in the StateMachine and recovered gracefully.

I had initially planned to leave this till I was further along refactoring the conhost side of things, but maybe it's a good idea to get it done sooner rather than later if it'll save users from having a crashed terminal. Any objections to that?

I should add that this isn't necessarily a fix for the OSC 9;9 handling - I'm not sure what the correct behaviour is for that. I just want to make sure the terminal isn't needlessly crashing in situations like this.

I agree. At the very least, we should fix this crash now, so we can service the fix to the in-market builds.

I am gonna move it out of the 1.14 milestone though, just for the sake of work tracking.

Yeah, that makes perfect sense. I've just checked ConEmu now and it looks like a blank path is simply ignored, i.e. it retains the last valid path that was set. So what we have is technically correct - it's just a code health issue now.