Add error for unexpected arguments

server/server.go

@@ -41,6 +41,7 @@ var (
 	ErrNoSuchReceiver     = errors.New("no such receiver registered")
 	ErrNoSuchMethod       = errors.New("no such method was found")
 	ErrInvalidMethod      = errors.New("method invalid for lrpc call")
+	ErrUnexpectedArgument = errors.New("argument provided but the function does not accept any arguments")
 )
 
 // Server is an lrpc server
@@ -120,7 +121,10 @@ func (s *Server) execute(pCtx context.Context, typ string, name string, arg any,
 	// Get method type
 	mtdType := mtd.Type()
 
-	//TODO: if arg not nil but fn has no arg, err
+	// Return error if argument provided but isn't expected
+	if mtdType.NumIn() == 1 && arg != nil {
+		return nil, nil, ErrUnexpectedArgument
+	}
 
 	// IF argument is []any
 	anySlice, ok := arg.([]any)