Allow serial exceptions to be raised

from openflexure_stage import OpenFlexureStage

from serial import SerialException

from openflexure_microscope.lock import StrictLock

        """

        self.lock = StrictLock(timeout=2)  #: :py:class:`openflexure_microscope.lock.StrictLock`: Strict lock controlling thread access to camera hardware

        try:

        OpenFlexureStage.__init__(self, *args, **kwargs)

        except SerialException:

            logging.error("No stage found. Aborting stage.")

            logging.warning("Stage lock can be acquired, but any stage methods will fail and raise exceptions.")

    def _move_rel_nobacklash(self, *args, **kwargs):

        """

        Overrides :py:function:`openflexure_stage.stage.OpenFlexureStage._move_rel_nobacklash` to acquire lock first.

        """

        if self._ser:

            with self.lock:

                OpenFlexureStage._move_rel_nobacklash(self, *args, **kwargs)

        else:

            logging.warning("Unable to move stage. Serial communication unavailable.")