Cleanup handlers and test handlers

[MuckT]

• [x] Test 404 route tests.
• [x] Test 500 route tests.

You might need to add another sample route to the API to throw the bad response e.g.

// Bad route
app.get('/bad', (req, res, next) => {
  next('error message to send')
})

[vbchomp]

Done and merged.