Added a return to stop an error occuring on no connection

Author: iandobbie

microscope/stages/ludl.py

@@ -117,6 +117,7 @@ def __init__(self, port: str, baudrate: int, timeout: float) -> None:
                 answer = self.read_multiline()
             except:
                 print("Unable to read configuration. Is Ludl connected?")
+                return()
             # parse config responce which tells us what devices are present
             # on this controller.