Harper sometimes suggests "side affect" over "side effect"

**What got flagged?**
> I forgot to test the side effect that users are deleted when clearing data.

**Why is this incorrect?**
In this case, "side effect" serves as a noun.

Search the grammar rules and regression tests for the reported sentence and the "side affect" suggestion. Start with the rule that treats "affect" and "effect" as interchangeable, then add a focused test showing that "side effect" is accepted as a noun and verify the incorrect suggestion no longer appears.

Written by the indexing model from the issue text.