Do not include unused return expressions

[lukastaegert]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:
Resolves #4542

Description

When a function contains a return expression after an error, the argument of this return would be included even though it is unused in the final bundle. This is fixed here.

[github-actions]

Thank you for your contribution! ❤️

You can try out this pull request locally by installing Rollup via

npm install rollup/rollup#gh-4542-non-included-return-expressions

or load it into the REPL:
https://rollupjs.org/repl/?pr=4573

[codecov]

Codecov Report

Merging #4573 (e298b29) into master (f019fae) will decrease coverage by 0.00%.
The diff coverage is n/a.

❗ Current head e298b29 differs from pull request most recent head 71f83c3. Consider uploading reports for the commit 71f83c3 to get more accurate results

@@            Coverage Diff             @@
##           master    #4573      +/-   ##
==========================================
- Coverage   98.87%   98.86%   -0.01%     
==========================================
  Files         209      209              
  Lines        7350     7344       -6     
  Branches     2100     2098       -2     
==========================================
- Hits         7267     7261       -6     
  Misses         27       27              
  Partials       56       56              

Impacted Files	Coverage Δ
src/ast/nodes/CallExpression.ts	100.00% <ø> (ø)
src/ast/nodes/shared/MultiExpression.ts	100.00% <ø> (ø)

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