Highlighting a character before changing it prefixes intermediate input state

[Bilge]

If some characters are highlighted and then changed, the (live) output becomes corrupted, containing two states at once: the transitory state it would have been in if the character was first deleted, and also the output from the final version of the input. Pressing the delete key before typing the new character still behaves correctly.

[SjonHortensius]

The PHP-WASM is executed async from the main thread that clears the output - which most likely causes this bug