Wanakana bind prevents external IME from converting when hitting a conversion containing latin characters

[Kuuuube]

To reproduce:

1. Attach wanakana to a textarea using wanakana.bind (the wanakana website works fine for testing this)
2. Focus the textarea
3. Activate a Japanese IME
4. Type a word in the search bar that can be converted to something that contains half width latin characters (for example えいご which can convert to A5)
5. Attempt to convert the word to kanji using space and press space multiple times
6. Keep pressing space until you hit the latin character conversion

Upon hitting the latin character conversion in your IME, wanakana jumps in and kills the IME. In this example with えいご it is impossible for someone to convert えいご to an IME entry below the conversion of A5. Wanakana will convert A5 to ア5 regardless of if the user is still composing from the IME. (https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/isComposing)

Reported by a user using Google IME on Windows. Replicated by me using Mozc on Linux with both Firefox and Chromium.