Fix bug in reading position of xystage in metadata

ImageJ/script_mosaic_telemos.py

@@ -749,8 +749,12 @@ def getMMtiles(metadata, selected_roi, tilesondisk):
                             break
                     
                 else:
-                    xt[ind] = pl['DevicePositions'][0]['Position_um'][0]
-                    yt[ind] = pl['DevicePositions'][0]['Position_um'][1]
+                    # Find the name of the stage
+                    for dev in pl['DevicePositions']:
+                        if dev['Device'] == 'XYStage':
+                            xt[ind] = dev['Position_um'][0]
+                            yt[ind] = dev['Position_um'][1]
+                            break
 
             else:
                 IJ.log("[WARNING]: File %s listed on metadata does not exist on disk" % pl['Label'])