Missing executable does not throw an exception

[aidanheerdegen]

Recent issue with a malformed executable path only warned user and payu run submitted ok, and then the model error with a message that didn't give much information about the real problem

It looks like MPI_INIT failed for some reason; your parallel process is
likely to abort.  There are many reasons that a parallel process can
fail during MPI_INIT; some of which are due to configuration or environment
problems.  This failure appears to be an internal failure; here's some
additional information (which may only be relevant to an Open MPI
developer):
 PML add procs failed
 --> Returned "Error" (-1) instead of "Success" (0)

During payu setup the malformed path triggered this warning:

Setting up atmosphere
File not found: /g/data/ik11/inputs/acce ss-om2/bin/yatm_1bb8904.exe

but this should be an exception which stops setup finishing for executables.

Maybe add some logic here:

https://github.com/payu-org/payu/blob/master/payu/models/model.py#L289