bug #781 Fix #426: Prevent fatal error during unserialization (PatchRanger)
bug #781 Fix #426: Prevent fatal error during unserialization (PatchRanger)

This PR was merged into the 5.x branch.

Discussion
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Fix #426: Prevent fatal error during unserialization

## Description

Refer to #426 .
## Solution

I've looked for all of `__destruct()` implementations regarding cache usage. That was the only one - so it should completely fix the aforementioned issue.

Commits
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fb0379a Fix #426: Prevent fatal error during unserialization

c960657/swiftmailer,swiftmailer/swiftmailer,Rotzbua/swiftmailer,jamesggordon/swiftmailer,tweakers-dev/swiftmailer,michabbb-backup/swiftmailer,tweakers-dev/swiftmailer,voku/swiftmailer,voku/swiftmailer,gencer/swiftmailer,swiftmailer/swiftmailer,Rotzbua/swiftmailer,gencer/swiftmailer,michabbb-backup/swiftmailer,c960657/swiftmailer,jamesggordon/swiftmailer