API: validation: mention invalid method name (#8489)

1 files changed, 12 insertions, 6 deletions

diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 26b84b7cc7..6d0c270a51 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -312,24 +312,30 @@ static void handle_request(Channel *channel, msgpack_object *request)
     api_clear_error(&error);
     return;
   }
+
   // Retrieve the request handler
   MsgpackRpcRequestHandler handler;
+  Array args = ARRAY_DICT_INIT;
   msgpack_object *method = msgpack_rpc_method(request);
 
   if (method) {
     handler = msgpack_rpc_get_handler_for(method->via.bin.ptr,
                                           method->via.bin.size);
+    if (handler.fn == msgpack_rpc_handle_missing_method) {
+      String m = method->via.bin.size > 0
+        ? cbuf_to_string(method->via.bin.ptr, method->via.bin.size)
+        : cstr_to_string("<empty>");
+      ADD(args, STRING_OBJ(m));
+      handler.async = true;
+    } else if (!msgpack_rpc_to_array(msgpack_rpc_args(request), &args)) {
+      handler.fn = msgpack_rpc_handle_invalid_arguments;
+      handler.async = true;
+    }
   } else {
     handler.fn = msgpack_rpc_handle_missing_method;
     handler.async = true;
   }
 
-  Array args = ARRAY_DICT_INIT;
-  if (!msgpack_rpc_to_array(msgpack_rpc_args(request), &args)) {
-    handler.fn = msgpack_rpc_handle_invalid_arguments;
-    handler.async = true;
-  }
-
   RequestEvent *evdata = xmalloc(sizeof(RequestEvent));
   evdata->channel = channel;
   evdata->handler = handler;