Completion of error handling

[elfring]

Would you like to add more error handling for return values from functions like the following?

• pthread_create ⇒ main
• pthread_mutex_lock ⇒ thread_progress

[mario-campos]

Great catch! I've added a bit more error-handling, but I am ignoring pthread_mutex_lock and family in thread_progress for now, as those will require a bit more thought as to how to terminate gracefully.

[elfring]

💭 I became curious how the error detection and corresponding exception handling will evolve further.