Fixed typo in MySQL error handling

libStorage.js

@@ -55,7 +55,7 @@ function runSQL(sqlQuery, connection, callback = (err, rows) => {
                         return callback(err, undefined);                        
                 }
                 log.WARN(`Database connection is unavailable, waiting ${ retryTimeout / 1000 } seconds...`);
-                retry += 1
+                _retry += 1
                 // Wait for the retry timeout before trying the query again
                 setTimeout(runSQL(sqlQuery, connection, callback, _retry));
             }