[SalesForce] Debug or view status of a @future method

If your code is already asynchronous, you don't need to use a @future method to call out. So you can add checks for this sort of thing.

public static void makeCallout(/*params*/)
{
    if (!system.isFuture() && !system.isQueueable() && !system.isBatch()
    {
        makeCalloutAsync();
    }
}
@future
static void makeCalloutAsync(/*params*/)
{
    makeCallout(/*params*/);
}

First thing even though future methods are there for a while they are a thing of past. Going forward unless you have existing future code the suggestion is to move your code to Queueable apex. Think of Queueable apex as Future 2.0

Queueable or Future or Batch why do you need them to make a callout from trigger?

Because a callout has to be made asynchronously from apex trigger because callouts can hold your database transactions until they're completed. This could obviously cause significant contention with other transactions and impact performance. Now by making a asynchronous call you're running a separate independent transaction other than your current transaction and your dml's doesn't have to wait for your callout response. Read more about HTTP Callout from Triggers

Future method: The issue with future methods is that you cannot chain them.

Queueable: Queueable are much more flexible in terms of functionality compared to future methods. They can be chained like batch apex. You can also call a batch class or a future method from them.

Batch Apex: We typically prefer batch apex when we are dealing with huge data or trying to leverage relaxation of some of the governor limits like the number of records that can be queried or chunking the data based on scope and executing them in smaller batcher which acts as independent transaction, Even though these are much more powerful they needs to be used with much consideration. Read more about Is it advisable to call Batch from trigger

What exactly is Ideal for your case?

Queueable seems to be ideal in your situation. You can still prefer to use your if else logic but you else condition should be calling a Queueable instead or all together just call a Queueable class. What you will be getting doing this(Calling Queueable) is you bypass the callouts using asynchronous thread as well as you don't have to worry if it's a future or Queuable or even Batchable on the other end

Now there are lot more things I didn't cover in this answer but as far as you're error is concerned this should give you a decent understanding and nice head start.

Edit: Make sure to Implement Database.AllowsCallouts If you are trying to make callout from Queueable Context