Remove invalid starboards

jarvis/cogs/starboard.py

@@ -132,9 +132,12 @@ class StarboardCog(Scale):
         to_delete = []
         for starboard in starboards:
             c = await ctx.guild.fetch_channel(starboard.channel)
-            if c:
+            if c and isinstance(c, GuildText):
                 channel_list.append(c)
             else:
+                self.logger.warn(
+                    f"Starboard {starboard.channel} no longer valid in {ctx.guild.name}"
+                )
                 to_delete.append(starboard)
 
         for starboard in to_delete: