How do I find out where an unhandled promise rejection occured? [duplicate]

Answer 1

node's 'unhandledRejection' event should solve your mystery:

process.on('unhandledRejection', (reason, promise) => {
    console.warn('Unhandled promise rejection:', promise, 'reason:', reason.stack || reason);
});

https://repl.it/I3JJ/2