fix: generate_modules.sh for non-apptainer builds

Change-Id: I8bef8290fd95908d16630e8239830d26c3b01b2d

lib/yashchiki/generate_modules.sh

@@ -33,7 +33,7 @@ source "${PATH_MODULES}/\$(readlink -f /proc/\$\$/exe | xargs -r basename)"
 EOF
 
 # Provide MODULESHOME for all singularity environments
-cat <<EOF >> ${SINGULARITY_ENVIRONMENT}
+cat <<EOF >> ${SINGULARITY_ENVIRONMENT:-/environment.sh}
 MODULESHOME=${MODULESHOME}
 export MODULESHOME
 EOF
@@ -42,9 +42,11 @@ EOF
 # to use after sourcing /opt/init/modules.sh
 (
 IFS=$'\n'
+if [ -d "/opt/spack/share/spack/modules" ]; then
 for moduledir in $(find /opt/spack/share/spack/modules -mindepth 1 -maxdepth 1 -type d); do
 cat <<EOF >> "${TARGET}"
 export MODULEPATH="${moduledir}\${MODULEPATH:+:\${MODULEPATH}}"
 EOF
 done
+fi
 )