grammar - What's the proper way to refer to the form of a word that's improperly punctuated?

Example sentence:

The Adventure's of Huckleberry Finn

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My dilemma:

I would like to convey to the writer of the example sentence that the word Adventure's, in its current _____ form, is grammatically incorrect (as opposed to its should-be plural form).

At first I started to use the word possessive to describe the form, but then I started thinking¹ that maybe, in the writer's mind, the word was in fact not written to represent possession but rather as a contraction of the words Adventure and is. In the latter case, I believe using the word contractional would be more appropriate than using the word possessive but since I don't know what the writer was (hypothetically) thinking when they wrote the word, I don't know which adjective to choose, if either.

I realize that chances are the writer just accidentally added an apostrophe where they shouldn't have, but that's neither here nor there.

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My question:

What's the best word to use to describe the current, incorrect form of the word Adventures as described above? Is there an all-encompassing word that would be a better fit than the words possessive, contractional, or a combination thereof?

Thanks!

¹ Yes, it hurt. ;)

Answer

Apostrophize - punctuate (a word) with an apostrophe

I would like to convey to the writer of the example sentence that the
word Adventure's, in its current apostrophized form, is grammatically

incorrect (as opposed to its should-be plural form).