Handle invalid JSON

[ojongerius]

In AWS I see a 502 with "Internal Server error".

Logs show Unexpected token _ in JSON at position 1

Reproduce:

▶ curl -XPOST -H 'Content-Type:application/graphql'  -d '{__schema { queryType { name, fields { name, description} }}}' https://hxtsoafqna.execute-api.us-east-1.amazonaws.com/stage/graphql
{"message": "Internal server error"}%

I guess we need to validate the payload before we continue.

Related: #174

[user512]

👋 @ojongerius, I took a look at this issue, I was wondering if it's a good idea to check valid JSON or empty body inside this try block?

open-api/src/handler.js

Lines 60 to 68 in dc7f111

	try {
	await connectToDatabase();
	} catch (err) {
	log('MongoDB connection error: ', err);
	// TODO: return 500?
	/* eslint-disable no-process-exit */
	process.exit();
	/* eslint-enable no-process-exit */
	}