[dwds] Error messages appear on hover over in VSCode debug console if the app is paused in JS

[annagrin]

The errors happen when to the app paused in JS code.

Suggestion:

• Add a separate category of errors in the expression compiler for when we can't evaluate due to missing frames.
• Do not show them as warnings in

  webdev/dwds/lib/src/services/chrome_proxy_service.dart

  Line 494 in 5fcbb80

  if (!result.type.startsWith('CompilationError')) {