Consider a PTS file that has a type error and then triggers a bug in the type checker (or probably anywhere else in the PTS interpreter)..
The type error will not be displayed immediately, because it will be recorded to be printed with all other type errors at the end.
Then the bug is triggered (for example an unmatched pattern) which will cause a Haskell exception to be displayed and this terminates the program without printing the type errors that occured before.
Consider a PTS file that has a type error and then triggers a bug in the type checker (or probably anywhere else in the PTS interpreter)..
The type error will not be displayed immediately, because it will be recorded to be printed with all other type errors at the end. Then the bug is triggered (for example an unmatched pattern) which will cause a Haskell exception to be displayed and this terminates the program without printing the type errors that occured before.