test-framework: Make pre-logger exceptions readable

Signed-off-by: Kamil Gierszewski <kamil.gierszewski@huawei.com>

core/test_run_utils.py

@@ -186,6 +186,8 @@ TestRun.setup = __setup
 
 @classmethod
 def __makereport(cls, item, call, res):
+    if cls.LOGGER is None:
+        return None
     cls.outcome = res.outcome
     step_info = {
         'result': res.outcome,