Red error messages are not cleared after I fix a bug in a notebook

[tomlarkworthy]

Describe the bug context: If a cell throws an error it shows it as red. Downstream cells also highlight the source of the error, in red, and display "jump to error".

If I fix the error cell, the downstream one does not clear unless it evaluate to a concrete value, so if it returns "invalidation", then the error is not cleared.

To Reproduce Go to https://observablehq.com/@tomlarkworthy/bug-unresolved-error-cells use toggle, note the last cell does not have its error markings removed