Fix radioreference query with subcat missing name

Some subcategories in RR are missing the scName attribute. This catches
that case and just uses an "Unknown" placeholder since all we are
using it for is status display.

Fixes: #10677

chirp/sources/radioreference.py

@@ -164,10 +164,15 @@ def do_fetch(self, status, params):
                                                                  self._auth)
                     self._freqs += result
                     status_cur += 1
+                    try:
+                        sc_name = subcat.scName
+                    except AttributeError:
+                        sc_name = 'Unknown Category'
+
                     status.send_status(
                         'Fetching agency %s %s:%s' % (agency.aid,
                                                       cat.cName,
-                                                      subcat.scName),
+                                                      sc_name),
                         status_cur / status_max * 100)
         status.send_end()