Fix get_errors method

There was a lot wrong with it, even though it has never, to my
knowledge, failed.

It used getattr incorrectly, without providing a default value of false, so
that if the attribute was not present on the object, an AttributeError would
be raised regardless.

It would fall back on the context ancestor if there wasn't a cause,
although I suspect it never did. This also was wrong, because the
context would not give any help in determining the error message.

Neither of these code defects is ever known to have caused a bug, but
the ruff linter run by CodeRabbit objected to the construction, and it
was correct.

Signed-off-by: mulhern <amulhern@redhat.com>

Author: mulkieran

src/stratis_cli/_error_reporting.py

@@ -79,16 +79,15 @@ def _interface_name_to_common_name(interface_name):
     raise StratisCliUnknownInterfaceError(interface_name)  # pragma: no cover
 
 
-def get_errors(exc: Exception):
+def get_errors(exc: BaseException):
     """
     Generates a sequence of exceptions starting with exc and following the chain
     of causes.
     """
-    while True:
-        yield exc
-        exc = getattr(exc, "__cause__") or getattr(exc, "__context__")
-        if exc is None:
-            return
+    yield exc
+    while exc.__cause__ is not None:
+        yield exc.__cause__
+        exc = exc.__cause__
 
 
 def _interpret_errors_0(error):