If the camera serialization fails, log a message rather than being si…

…lent.

glue_wwt/viewer/data_viewer.py

@@ -5,6 +5,7 @@
 from astropy.coordinates import SkyCoord
 import astropy.units as u
 from glue.core.coordinates import WCSCoordinates
+from glue.logger import logger
 from pywwt import ViewerNotAvailableError
 
 from .image_layer import WWTImageLayerArtist
@@ -85,7 +86,7 @@ def __gluestate__(self, context):
             }
             state["camera"] = camera
         except ViewerNotAvailableError:
-            pass
+            logger.error("Unable to export camera parameters as WWT viewer is not responding.")
         return state
 
     @classmethod