fix: build with --cfg=swc_ast_unknown

[timofei-iatsenko]

https://swc.rs/docs/plugin/ecmascript/compatibility#make-your-plugin-compatible

Enable backward compatibility for plugins

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.17%. Comparing base (4d28b7f) to head (8682ca8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #187   +/-   ##
=======================================
  Coverage   92.17%   92.17%           
=======================================
  Files           8        8           
  Lines        1355     1355           
=======================================
  Hits         1249     1249           
  Misses        106      106           

Flag	Coverage Δ
unittests	92.17% <ø> (ø)

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