unexpected formatting when replacing some range selections

[vthriller]

Steps to reproduce

• place cursor just outside of italic in "hello ┘italic and bold" (where "┘" represents cursor state)
• ctrl+→ twice to select "italic and"
• start typing

Expected

hello darkness bold

(similar to selection that includes before italic)

Got

hello darkness bold

[vthriller]

Similarly,

hello italic┘ and bold

Ctrl+→ to select " and", type "ized", expected

hello italicized bold

got

hello italicized bold