wcs: handle more errors from blurp (#7675)

combo/apps/wcs/models.py

@@ -267,9 +267,9 @@ class WcsFormsOfCategoryCell(WcsCommonCategoryCell, WcsBlurpMixin):
         context['slug'] = self.category_reference.split(':')[-1]
         context['title'] = self.cached_title
         context['description'] = self.cached_description
-        if 'forms' in context:
+        try:
             context['forms'] = list(context['forms'][self.wcs_site]['data'])
-        else:
+        except (KeyError, TypeError) as e:
             # an error occured in the blurp
             context['forms'] = []
         if self.ordering == 'alpha':