Clearing cache on error

[tomicvladan]

When trying to interact with some object that is cached but not available anymore, like a pod, directory, file etc., the application becomes completely unusable. Instead, it should be able to recognize such situation and invalidate cache and make the state consistent.

How to reproduce:

• Run the app using fdp-play.
• Create a pod, some directory and upload a file.
• Restart the fdp-play with the --fresh argument.
• Try to access the same pod and files again, upload a new file etc.