Accented characters cannot be entered correctly in macOS

Description

Accented characters cannot be entered correctly by long-pressing keys on macOS. The accented characters can be selected (either via mouse or number) but appear duplicated in the text together with the non-accented version (e.g. aä, uü, …).

To Reproduce…

Steps to reproduce the behavior:

  1. In the body of a new email long press “a”
  2. select the desired accented character from the pop-up
  3. character appears duplicated in the text

Expected Behavior

Accented characters should appear correctly without duplicates in the email body.

Screenshots

ezgif.com-gif-maker

Setup

  • OS and Version: macOS 10.15.7
  • Installation Method: homebrew cask or dmg
  • Mailspring Version: 1.8.0

Please let me know if there is additional information that I should provide, or if you have a hint on where the issue originates from.
Unfortunately this bug makes Mailspring unusable for language like German or others that heavily rely on accented characters.