One other note - we saw this again today and it happened with the "on block placed" command - no "on player walk" at all in this particular test.
My daughter was hitting this constantly today. The flower trail tutorial and the super digger both crashed quickly and repeatedly. It does seem like it might be related to the on player walk as Ryan suggested. We tried plenty of other tutorials and some random goofing around (mostly just automated block placement) and those were fine.
@Denis I'll add notes to the Github ticket this evening. I grabbed an app crash, an example MakeCode program, and some other version info I'm attaching to this case in case it helps the Mojang team.
Mojang Team - see the 4 new files I just attached to the issue. I get a crash 100% of the time I run that sample MakeCode program. It runs for maybe 1-3 seconds then a hard crash that kills the Minecraft app. I pulled the app crash report and attached it in case that has any tidbits of info that help. I also attached my Minecraft version + Windows 10 version info and the fault message from Event Viewer.
If there is a debugging tool I need to hook up to catch more details - I'm happy to install/run whatever is needed here. My daughter was really enjoying MakeCode and we've had to stop using it since she's getting really frustrated with the crashes. More than happy to help however I can.