[error-boundaries] Extend JSX detection to variable assignments inside try blocks

[Rel1cx]

Background

Per error-boundaries.spec.diff.md, the current error-boundaries rule only inspects ReturnStatement nodes for JSX inside try blocks, missing intermediate variable assignments.

React Compiler's ValidateNoJSXInTryStatement flags any JsxExpression / JsxFragment instruction.

Current behavior

function Component() {
  try {
    const el = <div />; // ❌ currently missed
    return el;
  } catch {}
}

Expected behavior

When traversing TryStatement, also detect JSX expressions inside VariableDeclarator, AssignmentExpression, and similar nodes.

References

• Diff report: plugins/eslint-plugin-react-x/src/rules/error-boundaries/error-boundaries.spec.diff.md (§2.1 / §7)
• SPEC: ValidateNoJSXInTryStatement

Priority

P0 — low implementation cost (extend existing visitor), high alignment benefit.