Crash when deleting block from page template

[startuptester]

Describe the bug
When I create a page using a template and then delete a block, the app crashes - and not very gracefully.

To Reproduce
Steps to reproduce the behavior:

1. In the app, create a new page using a template for a site with Jetpack installed. - I can only repro this on JP sites so far
2. In the editor, delete a pre-set block
   Crash
   https://cloudup.com/ctvbVn5iqHn

Expected behavior
Block deletes with no crash

Screenshots
https://cloudup.com/cN4cvHBFV0e

Smartphone (please complete the following information):
iPhone 12 Pro, iOS 14.2.1, WP 16.3 beta

Additional context
Add any other context about the problem here.

[guarani]

I can only repro this on JP sites so far

Just noting that I could reproduce this on a Simple WP.com site too