better single <infill> error handling

app.py

@@ -123,7 +123,9 @@ async def infill_maybe(info: str):
     temperature = float(form['temperature'])
     try:
         if len(form['parts']) > 2:
-            return {'result': 'error', 'text': ''.join(form['parts']), 'type': 'infill', 'message': f"error: Only a single infill is supported!"}
+            return {'result': 'error', 'text': ''.join(form['parts']), 'type': 'infill', 'message': f"error: Only a single <infill> token is supported!"}
+        elif len(form['parts']) == 1:
+            return {'result': 'error', 'text': ''.join(form['parts']), 'type': 'infill', 'message': f"error: Must have an <infill> token present!"}
         prefix, suffix = form['parts']
         generation = generate(prefix, suffix=suffix, temperature=temperature, max_new_tokens=length_limit, top_p=0.95, repetition_penalty=1.0)
         generation['result'] = 'success'