Exceptions
Defects in how exceptions are thrown and caught, where the type or handling of a fault misrepresents what actually happened. The common thread is a mismatch between the exception’s meaning and the program’s intent — a placeholder thrown from a path that ships, or a catch so broad it erases the diagnosis.
Throwing NotImplementedException or NotSupportedException leaves a stub masquerading as a real method, while a bare catch (Exception) that does nothing turns every fault — including the ones that signal corruption you must not continue past — into silence. Catch narrowly, and let what you cannot handle propagate.