I managed to reproduce 3 times from clean startup following crashes on Fornite for PC.
The reproduction steps are following:
Join Battle Royale Squad. At any moment after landing, go to Settings > Keyboard Controls, change keyboard shortcuts as follow: w → e, a → s, s-> d, d → f.
Try to Apply settings. The client should now be crashed and non responsive and the black window “Fortnite Crash Reporter” should appear.
Fortnite process has to be killed and keyboard settings changed when not in-game to be able to apply successfully the shortcut changes.