The parameter num_rows_in is defined as number(32,0). You should use number` without precision in this context to make the code compile.

See good and bad example in https://github.com/Trivadis/plsql-and-sql-coding-guidelines/blob/v4.1/docs/4-language-usage/7-stored-objects/9-sql-macros/g-7910.md