Observatory: LateInitializationError: Field '_varsDiv' has not been initialized.

[rakudrama]

I get this on every page when I single-step in observatory.

I think DebuggerFrameElement._varsDiv should be nullable, not late.
The value is tested for null.

Unexpected exception:

LateInitializationError: Field '_varsDiv' has not been initialized.

StackTrace:

main.dart.js 466:3     Object.f
main.dart.js 473:23    Object.b
main.dart.js 28446:39  en.gkB
main.dart.js 28607:13  en.zX
main.dart.js 1:1       Object.eval
main.dart.js 15955:30  Fc.$1
main.dart.js 39208:29  CC.$0
main.dart.js 39182:9   r2.n2
main.dart.js 39205:12  CD.$1
main.dart.js 39208:29  CC.$0
===== asynchronous gap ===========================