add BadRequestKeyError.show_exception #1592
See pallets/flask#3249. The behavior introduced in 0.15.0 was to show the error unless
Instead, add a
if app.debug: e.show_exception = True
While this is technically not backwards compatible, it adds information overall and sets a more secure default, and it was a fairly obscure and recent change to begin with, so I'm comfortable adding this to 0.15.5.