NullPointer excetpion during backup

my backup running fine for some time, but now I see this nullpointer exception. Any tips to resolve this error?

```
***ERROR*** NullPointerException - null
java.lang.NullPointerException
        at com.smartsheet.tools.SmartsheetBackupService.backupOrgTo(SmartsheetBackupService.java:115)
        at com.smartsheet.tools.SmartsheetBackupTool.main(SmartsheetBackupTool.java:107)
```
