If an user requests an AMI with unsupported instance type, scripts properly returns due error, however it hangs waiting for creation of instances that will be never created.

For example, providing ami-019af36249ca598da (Ubuntu 18.04 LTS latest, up to day) and t2.micro instance type, since they're not compatible, script hangs on >>> WAITING for the instances to become RUNNING.

Eh @labgua?