channel.c: refactor spaghetti code

channel.c: WIP remove redundant method check and added FUNC_ATTR_NONNULL_ALL macro

channel.c channel_defs.h helpers.c: added Error field to RequestEvent, added no_op handler func

channel.c: use const char* instead of string and cleanup

channel.c; channel_defs.h; helpers.c: removed error from event again; send errors directly to the channel without using handlers and events

channel.c: fixed memory leak and lint errors

api/private/dispatch.c; api/vim.c; msgpack_rpc/channel.c msgpack_rpc/helpers.c added Error* field to msgpack_get_handler_for; further refactored channel.c

channel.c:323 changed order of evaluation in if statement

channel.c: removed superflous whitespace

dispatch.c: review comment

2 files changed, 12 insertions, 8 deletions

diff --git a/src/nvim/api/private/dispatch.c b/src/nvim/api/private/dispatch.c
index 5207a57b88..2e59d3faa9 100644
--- a/src/nvim/api/private/dispatch.c
+++ b/src/nvim/api/private/dispatch.c
@@ -32,16 +32,19 @@ static void msgpack_rpc_add_method_handler(String method,
 /// @param name API method name
 /// @param name_len name size (includes terminating NUL)
 MsgpackRpcRequestHandler msgpack_rpc_get_handler_for(const char *name,
-                                                     size_t name_len)
+                                                     size_t name_len,
+                                                     Error *error)
 {
   String m = { .data = (char *)name, .size = name_len };
   MsgpackRpcRequestHandler rv =
     map_get(String, MsgpackRpcRequestHandler)(methods, m);
 
   if (!rv.fn) {
-    rv.fn = msgpack_rpc_handle_missing_method;
+    String method_name = m.size > 0 ?
+      m : cstr_as_string("<empty>");
+    api_set_error(error, kErrorTypeException, "Invalid method: %s",
+                  method_name);
   }
-
   return rv;
 }
 
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 002d9da781..03567ddfd8 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1162,11 +1162,12 @@ Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
     }
     Array args = call.items[1].data.array;
 
-    MsgpackRpcRequestHandler handler = msgpack_rpc_get_handler_for(name.data,
-                                                                   name.size);
-    if (handler.fn == msgpack_rpc_handle_missing_method) {
-      api_set_error(&nested_error, kErrorTypeException, "Invalid method: %s",
-                    name.size > 0 ? name.data : "<empty>");
+    MsgpackRpcRequestHandler handler =
+        msgpack_rpc_get_handler_for(name.data,
+                                    name.size,
+                                    &nested_error);
+
+    if (ERROR_SET(&nested_error)) {
       break;
     }
     Object result = handler.fn(channel_id, args, &nested_error);