Give an error when function with no argument is called with parentheses (or function with argument is called with no parentheses) in \tikzmath?

[user202729]

Brief outline of the proposed feature

\begin{tikzpicture}
    \node{
            \tikzmath{
                function g{
                    return 2;
                };
                real \i;
                \i=g;
                print{\i};
            }
            \tikzmath{
                function f(\x){
                    return \x;
                };
                real \i;
                \i=f;
                print{\i};
            }
        };
\end{tikzpicture}

Usage example

No response