Skype Preview users have been reporting that the app is crashing for Windows Insiders as well as some people in the Production Ring. According to Neowin, the problem started with the most recent version 184.108.40.206 across the board.
For the last 24 hours, users across the Skype community forum and various other methods have been reporting the crash on startup making the Skype Preview UWP app completely unusable for now.
Neowin suggests that users uninstall the Skype Preview app for now and simply use the original Skype desktop software for Windows instead. Having both can also cause issues as Microsoft attempts to usher more users into the UWP through notifications.
The only official statement so far is a comment by the Skype Team staff in the community forums less than an hour ago.
Thanks for reporting this issue. We're currently investigating this and will work on a fix as soon as possible.
It's a standard answer to many bug issues, but at least the team is aware and working on the app breaking fix. We'll keep you updated as more information arises here at OnMSFT or you can follow our Twitter feed for quick news.