Puppeteer: CSSCoverage is already enabled

CSS coverage is started while it is already enabled.

Error message

CSSCoverage is already enabled

How this error happens

Coverage collection has an enabled/disabled lifecycle. Starting CSS coverage twice without stopping it repeats an already-active operation.

The snippets use an open Chrome/CDP page named page.

await page.coverage.startCSSCoverage();
await page.coverage.startCSSCoverage();

How to fix

Start coverage once, perform the work, then stop it and read the result.

await page.coverage.startCSSCoverage();

try {
    await page.setContent(
        "<style>p { color: red; }</style><p>Hello</p>"
    );
} finally {
    const coverage = await page.coverage.stopCSSCoverage();

    console.log(coverage);
}

Things to keep in mind

Run the corrected sequence on a fresh page or after stopping the original collector. Starting again is not how you reset active coverage.

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