[react-devtools-shared] Fix URL construction when base URL is invalid

[KimCookieYa]

Problem

• Users encounter “Failed to construct 'URL': Invalid base URL” when clicking the “View source” action in DevTools if the underlying base URL is invalid.
• This exception originates from new URL(relative, base) and bubbles up, interrupting the DevTools UI.
• Fixes GitHub issue #34317

Solution

• Wrap URL construction to:
  • First try new URL(sourceMapAt, sourceURL).
  • If that fails, try new URL(sourceMapAt) as an absolute URL.
  • If both fail, return null (no symbolication) rather than throwing.
• This preserves normal behavior for valid bases and absolute URLs, while avoiding crashes for invalid bases.

Implementation details

• Updated symbolicateSource in packages/react-devtools-shared/src/symbolicateSource.js to handle invalid base URL scenarios without throwing.
• Added/verified tests in packages/react-devtools-shared/src/__tests__/utils-test.js:
  • “should not throw for invalid base URL with relative source map” → resolves to null.
  • “should resolve absolute source map even if base URL is invalid” → still resolves correctly.

Test plan

• Lint/format:
  • yarn prettier-check
  • yarn linc
• Type checking:
  • yarn flow dom-node
• Unit tests:
  • yarn test --watchAll=false utils-test
  • Optionally: yarn test --watchAll=false utils-test inspectedElement
• All of the above pass locally for experimental channel.

Risks and rollout

• Risk: Low. Only affects cases where the base URL is invalid.
• Normal cases (valid base or absolute sourceMappingURL) are unchanged.
• No user-facing API changes; DevTools UX becomes more resilient.

Affected packages

• react-devtools-shared

Related

• Fixes GitHub issue #34317

Checklist

• Ran yarn prettier-check
• Ran yarn linc
• Ran yarn flow dom-node
• Relevant unit tests passing
• Linked issue and added a concise summary

Summary

How did you test this change?

[hoxyq]

Thank you!