cubeviz spectral extraction: send exceptions to snackbar (spacetelesc…

…ope#2807)

* send exceptions to snackbar
* still should aim to *prevent* errors by disabling the button, whenever possible, but this can catch any remaining exceptions instead of burying them.
* changelog entry

CHANGES.rst

@@ -73,6 +73,8 @@ Bug Fixes
 Cubeviz
 ^^^^^^^
 
+- Spectral extraction errors will show in snackbar. [#2807]
+
 Imviz
 ^^^^^
 

jdaviz/configs/cubeviz/plugins/spectral_extraction/spectral_extraction.py

@@ -415,7 +415,12 @@ def get_aperture(self):
         return mask_weights
 
     def vue_spectral_extraction(self, *args, **kwargs):
-        self.collapse_to_spectrum(add_data=True)
+        try:
+            self.collapse_to_spectrum(add_data=True)
+        except Exception as e:
+            self.hub.broadcast(SnackbarMessage(
+                f"Extraction failed: {repr(e)}",
+                sender=self, color="error"))
 
     def vue_save_as_fits(self, *args):
         self._save_extracted_spec_to_fits()