fix(CI): check for existing mirror before adding or deleting local cache

install_spack_env.sh

@@ -81,9 +81,12 @@ spack spec aida
 # rebuild spack's database (could be an debugging session)
 spack reindex
 
-# TODO for newer spack versions, add: --autopush --unsigned, drop create cache command below
-# (Note: spack expects `build_cache/` below the folder we specify here
-spack mirror add local_cache ${SPACK_CACHE_BUILD}
+# add local mirror if it does not exist
+if [[ ! $(spack mirror list | grep local_cache) ]]; then
+    # TODO for newer spack versions, add: --autopush --unsigned, drop create cache command below
+    # (Note: spack expects `build_cache/` below the folder we specify here
+    spack mirror add local_cache ${SPACK_CACHE_BUILD}
+fi
 
 # install platform compiler (extract version from packages.yaml)
 if [ $SYSTEMNAME == ebrainslab ]
@@ -224,7 +227,9 @@ if [ $spack_install_ret -ne 0 ]; then
 fi
 
 # remove local cache content
-spack mirror destroy --mirror-name local_cache
+if [ -d ${SPACK_CACHE_BUILD} ]; then
+    spack mirror destroy --mirror-name local_cache
+fi
 
 # TODO: when using spack remote OCI build caches require an index file
 #spack mirror add ebrains oci://docker-registry.ebrains.eu/esd/build_cache