check if cache file exists before trying to read it

[Marmelatze]

This checks if the file exists, otherwise wenum may fail to start if the directory exists but not the cache.json

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The program was tested solely for our own use cases, which might differ from yours.

Florian Pfitzer florian.pfitzer@mercedes-benz.com, Mercedes-Benz Tech Innovation GmbH Provider Information

Licensed under GPL 2.0