False negative: Doesn't flag "show case" to become "showcase" in some real-word contextx

I noticed a comment on another GitHub project that used "show case" instead of "showcase" but Harper doesn't flag it. I was able to craft another context in which Harper does flag it.

Not the green dotted underline is Chrome flagging this. It's also worth noting that this context does not appear to be native English so it's hard to guess how common uses similar enough to this one are. Need to check if a naïve implementation will result in false positives.

No source file or test is identified in the issue. Start by reproducing the reported flagged and unflagged contexts in Harper, then locate the existing handling for “show case” and add regression coverage. Done means the intended context is flagged while similar legitimate uses do not produce false positives.

Written by the indexing model from the issue text.