Forward/Propagate the reason for a chunk error to errorChunks.dat

... this would be also very helpful for debugging.

Catching (via "try" block) should start in TM.io.get_ready_chunk() and then the exception should propagate through

• TM.io.get_ready_chunk
• mpi.TemplateMatchingTasks.preload_chunk()

and be considered in

• mpi.TemplateMatching.__reclaim_slaves()
• mpi.TemplateMatching.__save_status()
  • (finally saved to errorChunks.dat)