FIX ISSUE:#43878 when the vlans string have a final comma. (#43879)

lib/ansible/modules/network/ios/ios_l2_interface.py

@@ -303,11 +303,12 @@ def vlan_range_to_list(vlans):
         for part in vlans.split(','):
             if part.lower() == 'none':
                 break
-            if '-' in part:
-                start, stop = (int(i) for i in part.split('-'))
-                result.extend(range(start, stop + 1))
-            else:
-                result.append(int(part))
+            if part:
+                if '-' in part:
+                    start, stop = (int(i) for i in part.split('-'))
+                    result.extend(range(start, stop + 1))
+                else:
+                    result.append(int(part))
     return sorted(result)