Fix non-clearing output when nothing is outputted (#60)

When the the update does not print anything the output is not cleared,
since it waits for an output to be cleared. We fix this by printing an
empty string to invoke the clearning of the output

* Ignore B040 for checks failing

Through an update linter complained that no error message is raised, but
we do not want to raise an error message when one of the checks raises
one.

Author: agoscinski

src/scwidgets/check/_check.py

@@ -218,7 +218,9 @@ def check_function(self) -> ChecksResult:
             if self._fingerprint is not None:
                 try:
                     output = self._fingerprint(*output)
-                except Exception as exception:
+                except (  # we do not raise here since it is passed to widget output # noqa B040
+                    Exception
+                ) as exception:
                     if python_version() >= "3.11":
                         exception.add_note(
                             "An error was raised in fingerprint function, "

src/scwidgets/exercise/_widget_code_exercise.py

@@ -657,6 +657,11 @@ def _on_click_update_action(self) -> bool:
                 raised_error = True
                 raise e
 
+            # The clear_output command at the beginning of the function waits till
+            # something is printed. If nothing is printed, it is not cleared. We
+            # enforce it to be invoked by printing an empty string
+            print("", end="")
+
         return not (raised_error)
 
     def run_update(self):