Your resolution makes sense and I believe it should work. But, for me, it does not work yet.
I have deleted all Blocks and Related code as well, and I have deleted entire file that I have worked. lol
But, the error still continue.
It's gone from my store page, so I thought it should be okay, but it repeatedly came back when I start creating the Blocks. lol
It kills my whole day and it will continue to my second day. god...
Is there any option to expunge the previous error that I have made? (Actually, I was testing the upper/lower case letter and it trigged..k