Update on this issue by [~Mega_Spud]:
This issue seems to be triggered by using a shield to block many (if not all?) projectiles, including but not limited to:
Shulker Bullets
Splash Potions
Wither Attacks
Blaze Fireballs
This bug is a very devastating one especially when i can't open the game anymore and have to uninstall and reinstall the game. Please A.S.A.P. before someone else figure out this bug.
Linked issues
is duplicated by 10
BDS-1190
Fireballs hit shields crash
Resolved
MCPE-48155
Game crashes when you use a fishing rod against a sheild. By clicking the "fish" button, it will throw the hook and when it hits another player blocking with a sheild, it will crash
Resolved
MCPE-48195
New bug
Resolved
MCPE-48409
Witch throws potion while player is blocking with shield and crashes the game
Resolved
MCPE-48501
Blocking the Skulker projectile crashes app.
Resolved
5 more links
If you have a copy of the world available, you might like to upload a copy of it for investigation.
On Windows 10 you can use the Export world feature.
On Android or iOS you need to use a file explorer to navigate to Device storage > games > com.mojang > minecraftWorlds
On Xbox or Switch the only way is to upload it to a Realm, and then download the world on Windows 10 or Android/iOS.
If the world is larger than 10MB you can upload the world to OneDrive or a similar file sharing site, and then share the link.