[Frontend] Add Early Validation For Chat Template / Tool Call Parser (#9151)

Signed-off-by: Alex-Brooks <Alex.Brooks@ibm.com>

vllm/scripts.py

@@ -11,7 +11,8 @@ from openai.types.chat import ChatCompletionMessageParam
 
 from vllm.engine.arg_utils import EngineArgs
 from vllm.entrypoints.openai.api_server import run_server
-from vllm.entrypoints.openai.cli_args import make_arg_parser
+from vllm.entrypoints.openai.cli_args import (make_arg_parser,
+                                              validate_parsed_serve_args)
 from vllm.logger import init_logger
 from vllm.utils import FlexibleArgumentParser
 
@@ -142,7 +143,7 @@ def main():
     env_setup()
 
     parser = FlexibleArgumentParser(description="vLLM CLI")
-    subparsers = parser.add_subparsers(required=True)
+    subparsers = parser.add_subparsers(required=True, dest="subparser")
 
     serve_parser = subparsers.add_parser(
         "serve",
@@ -186,6 +187,9 @@ def main():
     chat_parser.set_defaults(dispatch_function=interactive_cli, command="chat")
 
     args = parser.parse_args()
+    if args.subparser == "serve":
+        validate_parsed_serve_args(args)
+
     # One of the sub commands should be executed.
     if hasattr(args, "dispatch_function"):
         args.dispatch_function(args)