[BUG/ISSUE] GCHP 12.7.0 standard run fails if emissions turned off

[lizziel]

Turning emissions off in input.geos (via runConfig.sh) and turning emissions off in HEMCO_Config.rc both cause GCHP runs to fail in 12.7.0. This issue is isolated to GCHP and does not occur in GEOS-Chem Classic.

If emissions are on in input.geos, but are turned off at the top of HEMCO_Config.rc, then I get this error in a standard simulation in the first timestep:

  --- Do emissions now
HEMCO (VOLCANO): Opening /n/holylfs/EXTERNAL_REPOS/GEOS-CHEM/gcgrid/gcdata/ExtData/HEMCO/VOLCANO/v2019-08/2016/07/so2_volcanic_emissions_Carns.20160701.rc
===============================================================================
GEOS-Chem ERROR: Error encountered in "HCOX_Run"!
 -> at HCOI_GC_Run (in module GeosCore/hcoi_gc_main_mod.F90)

THIS ERROR ORIGINATED IN HEMCO!  Please check the HEMCO log file for 
additional error messages!
===============================================================================

===============================================================================
GEOS-Chem ERROR: Error encountered in "HCOI_GC_Run"!
 -> at Emissions_Run (in module GeosCore/emissions_mod.F90)
===============================================================================

If emissions are instead off in input.geos, but are turned on at the top of HEMCO_Config.rc, then I get this error instead:

  --- Do convection now
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
===============================================================================
GEOS-Chem ERROR: Cannot get pointer to NOAA_GMD_CH4!
 -> at SET_CH4 (in module GeosCore/set_global_ch4_mod.F90)
===============================================================================

When emissions are off in both input.geos and HEMCO_Config.rc the input.geos emissions off problem occurs first.

  --- Do turbulence now
 vdinti: pbl height will be limited to bottom           25  model levels. top is
     431.250100000000       hpa
     ### Species Unit Conversion: kg/kg dry -> v/v dry ###
     ### VDIFFDR: VDIFFDR begins
     ### VDIFFDR: after emis. and depdrp
     ### VDIFFDR: before vdiff
     ### VDIFF: vdiff begins
     ### VDIFF: diffusion begins
     ### VDIFF: compute free atmos. diffusion
     ### VDIFF: pbldif begins
     ### VDIFF: after pbldif
     ### VDIFF: starting diffusion
     ### VDIFF: vdiff begins
     ### VDIFF: diffusion begins
     ### VDIFF: compute free atmos. diffusion
     ### VDIFF: pbldif begins
     ### VDIFF: after pbldif
     ### VDIFF: starting diffusion
     ### VDIFF: vdiff begins
===============================================================================
GEOS-Chem ERROR: Cannot get pointer to NOAA_GMD_CH4!
 -> at SET_CH4 (in module GeosCore/set_global_ch4_mod.F90)
===============================================================================

I have verified that the NOAA_GMD_CH4 is properly imported in MAPL, but there may be an issue on the HEMCO side of things, although the HEMCO.log file looks fine.

This issue needs more investigation and we will try to get a fix for 12.7.1.

[lizziel]

This issue is fixed in 12.7.1 with commit 5598d50.