While working on #9279 i noticed that a lot of exceptions raised often don't re-use the exception when raising;

# this
try:
  # yada
except Exception:
  raise CustomException()

# instead of this
try:
  # yada daba doo
except Exception as e:
  raise CustomException() from e

The latter adds more context and a longer and more detailed traceback to look at.

The request;

• Add more of these in a lot of places (either raise X from e, or putting them into twisted Failure objects that're thrown somewhere)
  • If it won't be added to the re-raised exception, put down a message why in the comment (sensitive information, etc.)

- (Maybe) Make it a coding policy/find a linter to enforce raised exception usage, unless explicitly suppressed.