Add _Good, _Bad, and _Ugly tests

[google-labs-jules]

This change refactors the existing tests to use the _Good, _Bad, and _Ugly testing convention. This provides a more structured approach to testing and ensures that a wider range of scenarios are covered, including valid inputs, invalid inputs, and edge cases. In addition to refactoring the tests, this change also includes several bug fixes that were uncovered by the new tests. These fixes improve the robustness and reliability of the codebase.

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PR created automatically by Jules for task 3577865431736069141 started by @Snider

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[codecov]

Codecov Report

❌ Patch coverage is 66.14907% with 109 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/all.go	52.00%	33 Missing and 3 partials ⚠️
cmd/serve.go	32.35%	22 Missing and 1 partial ⚠️
cmd/collect_website.go	60.41%	13 Missing and 6 partials ⚠️
pkg/pwa/pwa.go	70.58%	14 Missing and 1 partial ⚠️
cmd/compile.go	78.94%	4 Missing and 4 partials ⚠️
cmd/run.go	79.48%	4 Missing and 4 partials ⚠️

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