Improve error message when privateKey is not a single line String

[oscard0m]

Context: 40:09 in Reusing GitHub Apps and Actions with Gregor Martynus

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I can take it once we agree on how to tackle this :)

[gr2m]

Thanks for filing the issue! I think the right place to add better errors would be here:

auth-app.js/src/get-app-authentication.ts

Lines 10 to 14 in 348568d

	const appAuthentication = await githubAppJwt({
	id: +appId,
	privateKey,
	now: timeDifference && Math.floor(Date.now() / 1000) + timeDifference,
	});

We could wrap the code into a try/catch and in case of an error check if privateKey is only the first line of the private key, which is

-----BEGIN RSA PRIVATE KEY-----

And if it is, throw an error with a more helpful error message?

[github-actions]

🎉 This issue has been resolved in version 3.6.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀