BUG DETECTED: wait() error when using SwiftyRequest, CouchDB and NIO

[pixelfrei]

Description

When I load a json document with SwiftyRequest and then want to save it to CouchDB I get a BUG DETECTED: wait() error message from NIO.

Xcode stops the execution here:
https://github.com/apple/swift-nio/blob/main/Sources/NIO/EventLoopFuture.swift#L913

Environment Details

macOS 11.2.3
Xcode 12.4
Swift 5.3.2

Kitura 2.9.200
Kitura-NIO 2.4.200
SwiftyRequest 3.2.200
Kitura-CouchDB 3.2.0

Error message

Precondition failed: BUG DETECTED: wait() must not be called when on an EventLoop.
Calling wait() on any EventLoop can lead to
- deadlocks
- stalling processing of other connections (Channels) that are handled on the EventLoop that wait was called on

Further information:
- current eventLoop: Optional(SelectableEventLoop { selector = Selector { descriptor = 29 }, thread = NIOThread(name = NIO-ELT-1-#0), scheduledTasks = PriorityQueue(count: 0): [] })
- event loop associated to future: SelectableEventLoop { selector = Selector { descriptor = 45 }, thread = NIOThread(name = NIO-ELT-2-#0) }: file SwiftyRequest-CouchDB/.build/checkouts/Kitura-NIO/Sources/KituraNet/ClientRequest.swift, line 592
2021-03-15 11:55:50.415669+0100 SwiftyRequest-CouchDB[34611:5062052] Precondition failed: BUG DETECTED: wait() must not be called when on an EventLoop.
Calling wait() on any EventLoop can lead to
- deadlocks
- stalling processing of other connections (Channels) that are handled on the EventLoop that wait was called on

Further information:
- current eventLoop: Optional(SelectableEventLoop { selector = Selector { descriptor = 29 }, thread = NIOThread(name = NIO-ELT-1-#0), scheduledTasks = PriorityQueue(count: 0): [] })
- event loop associated to future: SelectableEventLoop { selector = Selector { descriptor = 45 }, thread = NIOThread(name = NIO-ELT-2-#0) }: file SwiftyRequest-CouchDB/.build/checkouts/Kitura-NIO/Sources/KituraNet/ClientRequest.swift, line 592

Example

let restRequest = RestRequest(method: .get, url: "RestApiUrl.json")

restRequest.responseObject() { (restResponse: Result<RestResponse<RestApiDocument>, RestError>) in
    switch restResponse {
    case .success(let result):
        if let document = result.body {
            self.services.couchDBService.retrieveDB("database") { (database, error) in
                guard let database = database  else {
                    Log.error("Database not found")
                    return
                }
                database.create(document) { (databaseResponse, error) in
                    if databaseResponse != nil {
                        Log.info("Successful created: \(String(describing: databaseResponse?.id))")
                    }
                }
            }
        }
    case .failure(let error):
        Log.error("Client request failed with \(error)")
    }
}