fix a bug with errors handling

src/jflow/workflow.py

@@ -429,9 +429,9 @@ class Workflow(threading.Thread):
         return gr
 
     def delete(self):
-        # first close the open files
-        self.stderrfh.close()
         if self.get_status() in [self.STATUS_COMPLETED, self.STATUS_FAILED, self.STATUS_ABORTED]:
+            # first close the open files
+            self.stderrfh.close()
             utils.robust_rmtree(self.directory)
 
     @staticmethod
@@ -951,14 +951,16 @@ class Workflow(threading.Thread):
         if not keep_same_error_file:
             if hasattr(self, "stderr") and self.stderr is not None:
                 os.rename( self.stderr, os.path.join(self.directory, str(time.time()) + self.STDERR_FILE_NAME + self.OLD_EXTENSION) )
+        
         stderr = os.path.join(self.directory, self.STDERR_FILE_NAME)
         logger = logging.getLogger( "wf." + str(self.id) )
         logger.setLevel(logging.DEBUG)
         formatter = logging.Formatter( '## %(asctime)s :: %(message)s' )
-        self.stderrfh = FileHandler(stderr, 'a')
-        self.stderrfh.setLevel(logging.ERROR)
-        self.stderrfh.setFormatter(formatter)
-        logger.addHandler(self.stderrfh)
+        if self.stderrfh is not None:
+            self.stderrfh = FileHandler(stderr, 'a')
+            self.stderrfh.setLevel(logging.ERROR)
+            self.stderrfh.setFormatter(formatter)
+            logger.addHandler(self.stderrfh)
         return stderr
 
     def _execute_weaver(self, engine_wrapper=None):