If your built code is crashing the editor, the easiest fix is to delete the
[project_folder]/.mono/temp and then start up the editor again.
This essentially resets the editor to have none of your code built, so it won't run the broken code. You can then try to fix the offending code or wrap it in try-catch and re-build from the editor.
Editor crashes should be reported, if not already. So just remember, if you find a crash, upvote the bug related to that specific crash type or open a new bug.