Missing variable

ci/stack_env.sh

@@ -25,6 +25,8 @@ if [ "$accelerator" != "none" ]
 then
     export acc_type=$(echo $env_json | jq -Mrc '.accelerator.type')
     export acc_arch=$(echo $env_json | jq -Mrc '.accelerator.arch')
+else
+    export acc_arch="none"
 fi
 
 echo "STACK_CONFIG_PATH: ${STACK_CONFIG_PATH}"