Enable fct thickness advection without tracer advection

Enable fct thickness advection without tracer advection and throw error
if using unsupported  combination of thickness and tracer advection.

Author: trhille

components/mpas-albany-landice/src/mode_forward/mpas_li_advection.F

@@ -484,8 +484,7 @@ subroutine li_advection_thickness_tracers(&
                   tend, advectedTracers, layerThicknessOld, &
                   layerThicknessEdge * layerNormalVelocity, 0 * normalVelocity, dt,    &
                   nTracers, activeTracerHorizontalAdvectionEdgeFlux, computeBudgets=.false.)!{{{
-         elseif ((trim(config_thickness_advection) .eq. 'fct') .and. &
-                  trim(config_tracer_advection) .eq. 'fct') then
+         elseif (trim(config_thickness_advection) .eq. 'fct') then
              ! Call fct routine for thickness first, and use activeTracerHorizontalAdvectionEdgeFlux
              ! returned by that call as normalThicknessFlux for call to tracer fct
              call li_tracer_advection_fct_tend(&
@@ -497,17 +496,25 @@ subroutine li_advection_thickness_tracers(&
              ! This does conserve mass:
              layerThickness(:,:) = layerThickness(:,:) + tend(nTracers,:,:) * dt
 
-             ! Call fct for tracers, using activeTracerHorizontalAdvectionEdgeFlux
-             ! from fct thickness advection as normalThicknessFlux
-             call li_tracer_advection_fct_tend(&
-                  tend(1:nTracers-1,:,:), advectedTracers(1:nTracers-1,:,:), layerThicknessOld, &
-                  activeTracerHorizontalAdvectionEdgeFlux(nTracers,:,:), 0.0_RKIND * normalVelocity, dt,    &
-                  nTracers-1, computeBudgets=.false.)
-         elseif ((trim(config_thickness_advection) .eq. 'fct') .and. &
-                  trim(config_tracer_advection) .eq. 'fo') then
+             if (trim(config_tracer_advection) .eq. 'fct') then
+                ! Call fct for tracers, using activeTracerHorizontalAdvectionEdgeFlux
+                ! from fct thickness advection as normalThicknessFlux
+                call li_tracer_advection_fct_tend(&
+                     tend(1:nTracers-1,:,:), advectedTracers(1:nTracers-1,:,:), layerThicknessOld, &
+                     activeTracerHorizontalAdvectionEdgeFlux(nTracers,:,:), 0.0_RKIND * normalVelocity, dt,    &
+                     nTracers-1, computeBudgets=.false.)
+             elseif (trim(config_tracer_advection) .eq. 'none') then
+                ! do nothing
+             else
+                err_tmp = 1
+                call mpas_log_write(trim(config_tracer_advection) // &
+                                    ' tracer advection is not currently supported with fct thickness advection.', MPAS_LOG_ERR)
+             endif
+         else
             err_tmp = 1
-            call mpas_log_write("config_tracer_advection = fo is not currently supposed &
-                                 with config_thickness_advection = fct", MPAS_LOG_ERR)
+            call mpas_log_write("config_thickness_advection = " // trim(config_thickness_advection) // &
+                                ", config_tracer_advection = " // trim(config_tracer_advection) // &
+                                " is not a supported combination.", MPAS_LOG_ERR)
          endif
 
          if (config_print_thickness_advection_info) then