Add message to suggest creation of directory SHPC

Inst_eddies/config.f90

 module config_m
 
+  use, intrinsic:: ISO_FORTRAN_ENV
+
   implicit none
 
   real, protected:: min_amp = 0.001
@@ -23,8 +25,9 @@ contains
 
     ! Local:
     logical exist
-    integer unit
+    integer unit, iostat
     namelist /config_nml/ min_amp, max_radius_deg, min_radius
+    character(len = 1000) iomsg
 
     !----------------------------------------------------------------------
 
@@ -44,7 +47,14 @@ contains
        read(unit, nml = config_nml)
        close(unit)
        open(unit, file = "SHPC/used_config_nml.txt", status = "replace", &
-            action = "write")
+            action = "write", iostat = iostat, iomsg = iomsg)
+
+       if (iostat /= 0) then
+          write(error_unit, fmt = *) "Have you created directory SHPC?"
+          write(error_unit, fmt = *) trim(iomsg)
+          stop 1
+       end if
+
        write(unit, nml = config_nml)
        close(unit)
     end if