completable_error.swift

let completable = Completable.create { observer in
    observer(.error(SomeError()))
    return Disposables.create()
}

// AS IS
completable.subscribe(onCompleted: {
    print("On Completed")
}, onError: { error in
    print("Got a error:", error)
}, onDisposed: {

}).disposed(by: disposeBag)
// Prints 
Got a error: SomeError()

// TO BE
Task {
    do {
        let value = try await completable.value
        print("Got a value:", value)
    } catch {
        print("Got a error:", error)
    }
}
// Prints 
Got a error: SomeError()