only attach reference message if not already known

discollama.py

@@ -103,15 +103,15 @@ async def on_message(message):
       if reference := message.reference:
         if session := load_session(message.reference):
           context = session.get('context', [])
-
-        reference_message = await message.channel.fetch_message(
-          reference.message_id)
-        reference_content = reference_message.content
-        raw_content = '\n'.join([
-          raw_content,
-          'Use it to answer the prompt:',
-          reference_content,
-        ])
+        else:
+          reference_message = await message.channel.fetch_message(
+            reference.message_id)
+          reference_content = reference_message.content
+          raw_content = '\n'.join([
+            raw_content,
+            'Use it to answer the prompt:',
+            reference_content,
+          ])
 
       async for buffer, chunk in buffered_generate_response(
           raw_content,