PromiseKit `Result.. is unused warning` in a chained sequence with a for loop

I have this annoying warning and I'm not able to get rid of it.
Let's say that I have a promise that sends a command to a bluetooth le device, to do a procedure I need to send these commands synchronously.
So what you can do in PromiseKit 6 is create a for loop and append each command using a then to the previous promise. The issue with that approach is that the compiler trigger a warning about an Result of call to 'then(on:flags:_:)' is unused, is like is missing the catch. I'm aware that I can use a cauterize() , but in this case I guess I will lost errors thrown while executing each promise. A when is not viable because it will execute concurrently while I need synchronously.
Here a small sample used with strings, in my real application they are NOT string.

 static func promise_startProcedure(with commands: [String]) -> Promise<Void> {
        let promise = Promise()
        for command in commands {
            promise.then { //<-- WARNING SHOW HERE
                Promise.value(command)
            }
        }
        return promise
    }

Is there a way to get rid of this warning?
[UPDATE]
I did a mistake, the answer was not correct bu pointed me to the right direction.

static func promise_startProcedure(with commands: [String]) -> Promise<Void> {
            var promise = Promise()
            for command in commands {
                promise = promise.then { 
                    Promise.value(command)
                }
            }
            return promise
        }

Try this. I just added Underscore to suppress the warning and did not get that warning.

static func promise_startProcedure(with commands: [String]) -> Promise<Void> {
    let promise = Promise()
    for command in commands {
        _ = promise.then {
            Promise.value(command)
        }
    }
    return promise
}