add check path to read folder

sohstationviewer/model/reftek_data/reftek.py

@@ -129,6 +129,8 @@ class RT130(GeneralData):
             total = sum([len(files) for _, _, files in os.walk(self.dir)])
 
         for folder in folders:
+            if not os.path.isdir(folder):
+                raise ProcessingDataError(f"Path '{folder}' not exist")
             for path, subdirs, files in os.walk(folder):
                 for file_name in files:
                     if self.creator_thread.isInterruptionRequested():