refactor(plexus): migrate SvgEdges to functional component (#3397)

[hharshhsaini]

Which problem is this PR solving?

Resolves #3397

Part of the larger refactoring effort tracked in #2610 to modernize Jaeger UI codebase by migrating class components to functional components

Description of the changes

• Converted SvgEdges class component to functional component in packages/plexus/src/Digraph/SvgEdges.tsx
• Replaced shouldComponentUpdate lifecycle method with React.memo() using a custom areEqual comparison function
• Preserved exact same update optimization logic including the isSamePropSetter utility for setOnEdge prop comparison
• Maintained TypeScript type safety with proper type assertions for generic props support
• Component behavior remains identical only re-renders when specific props change

Migration details:

• Converted class declaration to functional component
• Removed this.props references and render() method
• Preserved performance optimization with React.memo custom comparator
• Maintained all PropTypes validations
• No changes to component API or public interface

How was this change tested?

• All existing plexus unit tests passing (18 tests)
• Ran npm run lint - no linting errors
• Ran npm test - all tests pass
• Code formatted with Prettier
• Verified only SvgEdges.tsx was modified (no unintended file changes)
• Manual verification: component renders edges correctly with same visual output
• Performance: verified component only re-renders when relevant props change (same as original behavior)

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md

• I have signed all commits

• I have added unit tests for the new functionality (N/A - existing tests cover functionality)

• I have run lint and test steps successfully

• for jaeger-ui: 'npm run lint' and 'npm run test'

[github-actions]

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[github-actions]

PR quota unlocked! @hharshhsaini, this PR has been moved out of the waiting room and into the active review queue. Thank you for your patience.

Current Status: 8/2 open.

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[jkowall]

The CI failure is a TypeScript error at SvgEdges.tsx line 36:

TS2352: Conversion of type 'MemoExoticComponent<(<T = {}>(props: TProps<T>) => Element[])>'
to type '<T = {}>(props: TProps<T>) => Element[]' may be a mistake because neither type
sufficiently overlaps with the other.

The issue is the final cast as typeof SvgEdges. React.memo returns a MemoExoticComponent whose return type is ReactNode (which includes Promise<AwaitedReactNode> in newer React types), and that doesn't overlap with Element[] (the array return of SvgEdges). TypeScript rejects the direct cast.

Fix by casting through unknown:

-}) as typeof SvgEdges;
+}) as unknown as typeof SvgEdges;

This is the standard pattern for generic memoized components. Note that SvgEdgesLayer.tsx gets away with as typeof SvgEdgesLayer (no unknown) because it returns a single JSX.Element from <SvgLayer>, not an Element[] array.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.69%. Comparing base (c043a42) to head (620d801).
⚠️ Report is 26 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/plexus/src/Digraph/SvgEdges.tsx	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3518      +/-   ##
==========================================
+ Coverage   88.60%   88.69%   +0.08%     
==========================================
  Files         299      300       +1     
  Lines        9484     9559      +75     
  Branches     2500     2535      +35     
==========================================
+ Hits         8403     8478      +75     
+ Misses       1078     1077       -1     
- Partials        3        4       +1     

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[hharshhsaini]

@jkowall The TypeScript casting error (TS2352) in SvgEdges.tsx is fixed by casting through unknown. The branch has also been rebased on the latest jaegertracing:main to keep it up to date.

CI should be passing now. Please let me know if there's anything else.

[hharshhsaini]

@jkowall sir , did the desired changes I think its ready to merge , PTAL.

[jkowall]

Thanks, approved.

[hharshhsaini]

@jkowall Thanks for the approval sir.