Don't die when masking log.exception when there is no exception (ap…

…ache#16047)

It is possible that `exc_info` can be set, but contain no exception.

We shouldn't fail in this case, even if the output doesn't make sense as
shown by the test (the `NoneType: None` line is the exception being
logged.)

(cherry picked from commit 2f77633)

airflow/utils/log/secrets_masker.py

@@ -155,7 +155,7 @@ def filter(self, record) -> bool:
                 if k in self._record_attrs_to_ignore:
                     continue
                 record.__dict__[k] = self.redact(v)
-            if record.exc_info:
+            if record.exc_info and record.exc_info[1] is not None:
                 exc = record.exc_info[1]
                 # I'm not sure if this is a good idea!
                 exc.args = (self.redact(v) for v in exc.args)

tests/utils/log/test_secrets_masker.py

@@ -97,6 +97,21 @@ def test_exception(self, logger, caplog):
             """
         )
 
+    def test_exception_not_raised(self, logger, caplog):
+        """
+        Test that when ``logger.exception`` is called when there is no current exception we still log.
+
+        (This is a "bug" in user code, but we shouldn't die because of it!)
+        """
+        logger.exception("Err")
+
+        assert caplog.text == textwrap.dedent(
+            """\
+            ERROR Err
+            NoneType: None
+            """
+        )
+
     @pytest.mark.xfail(reason="Cannot filter secrets in traceback source")
     def test_exc_tb(self, logger, caplog):
         """