Script bails if a zone doesn't exist

[TheFiZi]

Describe the bug
I recently got rid of two of my domains and forgot to update my config.json. When cloudflare-ddns had to fire because my IP changed it hit the first zone in the configuration file, which didn't exist anymore in CF, got an error from the Cloudflare API and stopped processing the remaining domains.

To Reproduce
Steps to reproduce the behavior:

1. Delete a zone from Cloudflare
2. Run start-sync.sh

Expected behavior
Throw an error about the zone not existing anymore in CF and continue processing the rest of the zones in the configuration file.

Screenshots
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Additional context
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