Reproduction steps:
1. Create a new Project
2. In the Menu Bar, click Unity -> Shortcuts...
3. Double click any shortcut to edit it
4. Change it to an already used key in that Shortcut's Category (for example, the S key for 3D Viewport Category)
5. When the "Binding Conflict" dialog pops up, press any key on the keyboard

Reproducible with: 2021.2.0a5, 2021.2.0a14
Not reproducible with: 2018.4.34f1, 2019.4.25f1, 2020.3.5f1, 2021.1.4f1, 2021.2.0a4

First lines of the stack trace:
#0 0x007fff6e06233a in __pthread_kill
#1 0x007fff6dfe9808 in abort
#2 0x007fff6b248458 in abort_message
#3 0x007fff6b2398bf in demangling_unexpected_handler()
#4 0x007fff6cd745a9 in _objc_terminate()
#5 0x007fff6b247887 in std::__terminate(void (*)())