ESM1.6: Abort for failed coupling nml

[blimlim]

ESM1.6 very occasionally fails with the error

 ice: error reading coupling namelist in "input_ice.nml"

See here for an example. Rerunning usually resolves the issue, however it seems to stem from a failure when opening the input_ice.nml namelist.

cice5/drivers/access/cpl_parameters.F90

Lines 210 to 220 in 831e2eb

	open(unit=nu_nml,file="input_ice.nml",form="formatted",status="old",iostat=nml_error)
	!
	if (my_task == master_task) then
	write(ice_stdout,*)'CICE: input_ice.nml opened at unit = ', nu_nml
	endif
	!
	if (nml_error /= 0) then
	nml_error = -1
	else
	nml_error = 1
	endif

When the namelist open fails, nml_error is set to -1. This then skips the namelist reading and triggers the error reading coupling namelist in "input_ice.nml" further down.

We should abort directly after the failed open to make the cause of the crash clearer.