I tried to look back to find the exact example, but couldn't find anywhere that I had written it down. It was something where the $condition was a single word,

I tried to look back to find the exact example, but couldn't find anywhere that I had written it down. It was something where the $condition was a single word, referring to a boolean variable, but was not itself an adjective. By removing the "is true" clause, the clause was left without a verb, and without an antecedent.