fix: jsx types

[johnjenkins]

What is the current behavior?

GitHub Issue Number: N/A

What is the new behavior?

Fixes: #5306
Closes: #5307

TypeScript now correctly resolves Stencil's JSX element type.
Previously, JSX.Element was undefined in the h namespace, causing TypeScript to silently fall back to any for JSX expressions — surfaced as no-unsafe-return errors in strict @typescript-eslint setups.

Three type-level changes:

h.JSX.Element is now VNode
Host and Fragment are typed as (props) => VNode instead of FunctionalComponent<...>
FunctionalComponent<T> return type narrowed from VNode | VNode[] | null to VNode | null

Migration

No runtime changes — types only.

If you have a FunctionalComponent<T> that returns an array (via utils.map or similar), wrap the result in a fragment instead:

// Before
const MyList: FunctionalComponent<Props> = (props, children, utils) =>
  utils.map(children, transform);

// After
const MyList: FunctionalComponent<Props> = (props, children, utils) => (
  <>{utils.map(children, transform)}</>
);

Documentation

Does this introduce a breaking change?

• Yes
• No

Testing

Other information