This is a major problem for me at the moment, I turned on the experimental “Blueprint Break on Exceptions” option to track down a bug, and now a slightly different bug (a missing isValid in a blueprint initialization) is causing the editor to get stuck in a loop on startup when running the project. This is because the exception is thrown during asset initialization (It’s an AnimBP which should never exist in the game without a corresponding owner, but is initialized without an owner active), which causes the engine to get stuck in a permanent loop of failing to initialize the asset.
This functionality is useful for PIE functionality, but it’s potentially CATASTROPHICALLY bad if it’s run during initial compilation or construction of assets when the editor opens a project, it means any bug which compiles can throw an error that can never be gotten out of because the editor gets stuck permanently in Read-Only mode (as it breakpoints every time it fails during construction) which prevents FIXING the bug.
EDIT: In fact because it refuses to finish compiling you can’t even disable the setting from the editor settings menu, because the editor is locked in PIE mode! The only way out is to manually rewrite the editor settings ini file for the project