Is there a way to avoid the use of some-complex-expression in
thix formula?

if(isna(some-complex-expression); 0; some-complex-expression)

In some programming languages, 0 means false and any other
value means true and the OR(X,Y) actually means: if(X;X;Y).
Thus, you can use the OR as a shortcut for this if-statement
and avoid notation and evaluation of X, twice.

But Exel's OR returns TRUE or FALSE...

So: Is there any way to shorten

if(isna(some-complex-expression); 0; some-complex-expression)