lost-in-callbacks.js

/*
The number of stack frames that can
 (reasonably) be tracked is small (~dozens).

When you run code like below, the inner async `writeFile` 
can 'lose' its prior frame(s) 2 main ways:

1. When the outer `forEach` completes (w/ asyncs still running)
 the stack pops off the completed synchronous frames into
 the ether. Any later failure may only have a bit of async
 framework functions to reference.

2. A lot of (sync) code after `forEach` can push frames out of the debuggers view.*

*/
const files = ['file1', 'file2', 'file3']
files.forEach(file => {
  // This `writeFile()` might as well be shot into space
  fs.writeFile(file, `name: ${file}`, (err, data) => {
    // FACT: if a callback falls in space, no user will hear it*
  })
})
// [disclaimer: The stack cannot jettison things into space...] 
// [Also: Liberties were taken describing stack. #sorrynotsorry CS friends 😇]

the-promised-lost-stack.js

// Solution (Promises Version)
const files = ['file1', 'file2', 'file3']

const runningTasks = files.map(file => {
  // **return on your async call*** (and if needed, chain additional calls)
  return fs.writeFileAsync(file, `name: ${file}`, 'utf8')
})
// Now we can feed the tasks into a `Promise.all()`
(async () => {
  try {
    const completedTasks = await Promise.all(runningTasks)
    console.log(completedTasks)
  } catch (error) {
    // we can find what's going on here:
    console.error('WILL HAVE USEFUL STACK TRACE:', error)
  }
})

// Note: This pattern takes a _tiny_ bit more RAM
//   make sure to test in super constrained environments.