Nicer error message for unknown models with -c mode, closes #92

llm/__init__.py

@@ -79,7 +79,7 @@ def get_model(name):
     try:
         return aliases[name]
     except KeyError:
-        raise UnknownModelError(name)
+        raise UnknownModelError("Unknown model: " + name)
 
 
 def get_key(key_arg, default_key, env_var=None):

llm/cli.py

@@ -5,6 +5,7 @@ from llm import (
     Conversation,
     Response,
     Template,
+    UnknownModelError,
     get_key,
     get_plugins,
     get_model,
@@ -184,7 +185,10 @@ def prompt(
     conversation = None
     if conversation_id or _continue:
         # Load the conversation - loads most recent if no ID provided
-        conversation = load_conversation(conversation_id)
+        try:
+            conversation = load_conversation(conversation_id)
+        except UnknownModelError as ex:
+            raise click.ClickException(str(ex))
 
     # Figure out which model we are using
     if model_id is None: