fixes #1042: overlay doesn't clear if errors are fixed but warnings remain

[shellscape]

What kind of change does this PR introduce?
Bugfix for #1042

Did you add or update the examples/?

No need

Summary
#1042

Does this PR introduce a breaking change?
Negatory

Other information
None

[codecov]

Codecov Report

Merging #1043 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1043   +/-   ##
=======================================
  Coverage   72.25%   72.25%           
=======================================
  Files           4        4           
  Lines         465      465           
  Branches      139      139           
=======================================
  Hits          336      336           
  Misses        129      129

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