gcode: Reset current position after an endstop error

If the printer is commanded to an invalid location, reset the current
position to the last successfully commanded position.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/gcode.py

@@ -228,6 +228,7 @@ class GCodeParser:
             self.toolhead.move(self.last_position, self.speed, sloppy)
         except homing.EndstopError, e:
             self.respond("Error: %s" % (e,))
+            self.last_position = self.toolhead.get_position()
     def cmd_G4(self, params):
         # Dwell
         if 'S' in params: