CLDSRV-973: keep serving when the delete path throws synchronously

lib/services.js

@@ -425,12 +425,25 @@ const services = {
         const objGetInfo = objectMD.location;
         // special case that prevents azure blocks from unecessary deletion
         // will return null if no need
-        return data.protectAzureBlocks(bucketName, objectKey, objGetInfo, log, err => {
-            if (err) {
-                return cb(err);
-            }
-            return deleteMDandData();
-        });
+        // A synchronous throw in the data layer (e.g. no backend client for a location
+        // that was removed from the overlay) must not escape into the promise machinery:
+        // it surfaces there as an unhandledRejection and takes the whole process down.
+        try {
+            return data.protectAzureBlocks(bucketName, objectKey, objGetInfo, log, err => {
+                if (err) {
+                    return cb(err);
+                }
+                return deleteMDandData();
+            });
+        } catch (err) {
+            log.error('deleteObject: error protecting azure blocks', {
+                method: 'services.deleteObject',
+                error: err.message,
+                bucketName,
+                objectKey,
+            });
+            return cb(errors.InternalError);
+        }
     },
 
     /**