It seems that not adding a newline after a comment (e.g. "// my comment") produces an error ("No closing brace found").
In other words a // comment must not terminate the expression field.
For example, this simple opacity expression will not work:
Code: Select all
random(100); // this is a comment
Code: Select all
random(100); // this is comment
Using "/* this is a comment */" commenting style works in both cases.