Unless you're doing a challenge where the goal is to make a script containing the fewest possible characters, it's best to use the appropriate level of parenthesis, especially since that makes the script much easier to read. I confess I've skipped answering some forum posts because the lack of parenthesis has made them harder to read and understand. It also helps when forum posts include the CODE tag

generates the error you describe:
Code
//var %wildtest test*.test | if *. isin %wildtest //set %wildtest2 $remove(%wildtest , *. )


does not:
Code
//var %wildtest test*.test | if (*. isin %wildtest) //set %wildtest2 $remove(%wildtest , *. )