assertion failure in async bdd feature step does not fail the scenario

[RohanHart]

What are you trying to achieve?

Add a custom assertion to an async bdd step.

eg.,
Then(..., async () => {
const data = await I.grabTextFrom(...)
ok(data === 'foo')
}

What do you get instead?

the scenario is incorrectly marked successful and also raises an UnhandledPromiseRejectionWarning

Details

• CodeceptJS version: 2.0.4
• NodeJS Version: 8.11.4
• Operating System: Linux
• Puppeteer: 1.11.0

[RohanHart]

Looking deeper it seems that the typescript step definition is not being recognised as async in isAsyncFunction.

As it is not an error to await a non-promise (they are treated as resolved promises) the simple fix is #1526