server: Increase leniency to list templates on secondary stores that have been marked deleted by updating the db (#4713)

This PR aims at restoring the previous level of leniency in listing templates on stores that have been marked as deleted / removed by updating the DB.
While Cloudstack doesn't allow deleting stores that have resources on them, it may so happen that users may mimic a deletion of a store by merely updating the DB. Under such a case, listing of templates is hampered due to an NPE that is caused. (as seen in #4606)

Co-authored-by: Pearl Dsilva <pearl.dsilva@shapeblue.com>

Author: Pearl1594

server/src/main/java/com/cloud/api/query/dao/TemplateJoinDaoImpl.java

@@ -30,6 +30,7 @@
 import com.cloud.deployasis.TemplateDeployAsIsDetailVO;
 import com.cloud.deployasis.dao.TemplateDeployAsIsDetailsDao;
 import org.apache.cloudstack.api.ApiConstants;
+import org.apache.cloudstack.storage.datastore.db.ImageStoreVO;
 import org.apache.cloudstack.utils.security.DigestHelper;
 import org.apache.log4j.Logger;
 import org.springframework.stereotype.Component;
@@ -161,10 +162,13 @@ public TemplateResponse newTemplateResponse(EnumSet<ApiConstants.DomainDetails>
         HashMap<String, String> downloadDetailInImageStores = null;
         for (TemplateDataStoreVO templateInStore : templatesInStore) {
             downloadDetailInImageStores = new HashMap<>();
-            downloadDetailInImageStores.put("datastore", dataStoreDao.findById(templateInStore.getDataStoreId()).getName());
-            downloadDetailInImageStores.put("downloadPercent", Integer.toString(templateInStore.getDownloadPercent()));
-            downloadDetailInImageStores.put("downloadState", (templateInStore.getDownloadState() != null ? templateInStore.getDownloadState().toString() : ""));
-            downloadProgressDetails.add(downloadDetailInImageStores);
+            ImageStoreVO datastore = dataStoreDao.findById(templateInStore.getDataStoreId());
+            if (datastore != null) {
+                downloadDetailInImageStores.put("datastore", datastore.getName());
+                downloadDetailInImageStores.put("downloadPercent", Integer.toString(templateInStore.getDownloadPercent()));
+                downloadDetailInImageStores.put("downloadState", (templateInStore.getDownloadState() != null ? templateInStore.getDownloadState().toString() : ""));
+                downloadProgressDetails.add(downloadDetailInImageStores);
+            }
         }
 
         TemplateResponse templateResponse = new TemplateResponse();