Syntax error when attempting to do work in .then{} prior to executing next Promise function

```swift
getEventsFromDatabase(for: today)
.then { data in
// Diff
self.getEventsFromNetwork(for: today, event: data)
}
.then { data in
self.progress.progress = 0.5
self.parsePDF(data)
}
.then { data in
self.progress.progress = 0.5
self.updateViewData(for: self.todayEvents, data: data)
}
```

The above code works as advertised in the documentation.

```swift
getEventsFromDatabase(for: today)
.then { data in
self.progress.progress = 0.2 // Diff
self.getEventsFromNetwork(for: today, event: data)
}
.then { data in
self.progress.progress = 0.5
self.parsePDF(data)
}
.then { data in
self.progress.progress = 0.5
self.updateViewData(for: self.todayEvents, data: data)
}
```

In the first closure I add a block of code to update the UIProgressView.

Syntax error: Missing return in a closure expected to return 'Promise'

A look at the individual function differences:

### 1

```swift
private func getEventsFromDatabase(for date: Date) -> Promise<[NonCodableEvent]> {
return Promise {
return try DatabaseController.getEventsForDate(date: date, container: self.persistentContainer)
}
}
```

### 2

```swift
private func getEventsFromNetwork(for date: Date, event: [NonCodableEvent]) -> Promise {
if(event.count > 0) {
return Promise(on: .global()) { () -> [NonCodableEvent] in
return event
}
}

return Promise(on: .global()) { () -> Any in
let (data, response, error) = ServiceLayer().request(route: NavyRoute(squadron: Squadron.ht8, date: date))
if let error = error {
throw error
}

//TODO: Handle response code issues

return data
}
}
```

In '1', I'm returning a "generic" promise on the .main thread.
In '2', I'm returning a Promise explicitly run on the .global thread.

Trying to wrap my head around why this might be causing issues, or if there's something else I'm missing.