Fix instance where renderToStringAsync returns a promise of a promise

[ccouzens]

Fixes #377

I have had this happen with a project I work on. This includes a minimal test reproduction of it.

[changeset-bot]

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Latest commit: 7bd6b29

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
preact-render-to-string	Patch

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[JoviDeCroock]

We might also want to try a test where it's triple-y nested as it might warrant a loop similar to the Array.isArray one.

[ccouzens]

What do you think this would look like?

If I do something like:

		const Context = createContext();

		let c = 0;

		const Fetcher = ({ children }) => {
			c++;
			if (c === 1) {
				throw Promise.resolve();
			}
			return <Fragment>{children}</Fragment>;
		};

		const LazyComponent = lazy(
			async () =>
				function ImportedComponent() {
					return <div>2</div>;
				}
		);

		const NestedLazyComponent = lazy(
			async () =>
				function ImportedComponent() {
					return (
						<Context.Provider>
							<Fetcher>
								<LoadableComponent />
							</Fetcher>
						</Context.Provider>
					);
				}
		);

		const LoadableComponent = ({}) => (
			<Suspense fallback={'...loading'}>
				<LazyComponent />
			</Suspense>
		);

		const NestedLoadableComponent = ({}) => (
			<Suspense fallback={'...loading'}>
				<NestedLazyComponent />
			</Suspense>
		);

		const rendered = await renderToStringAsync(
			<Context.Provider>
				<Fetcher>
					<NestedLoadableComponent />
				</Fetcher>
			</Context.Provider>
		);

		expect(rendered).to.equal(`<div>2</div>`);

Then the current solution continues to work

[ccouzens]

The git commit formatter hook makes these changes. Let me know if you want me to keep them as is.

[JoviDeCroock]

Have you tried breaking it by increasing the nesting even further? Just wondering 😅