Fix assert condition in QEMU VMs

[ricab]

Fix an assert condition when making a new snapshot of a QEMU VM.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.89%. Comparing base (1affcb3) to head (96ad6b5). Report is 4 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3482 +/- ## ======================================= Coverage 88.89% 88.89% ======================================= Files 254 254 Lines 14081 14081 ======================================= Hits 12517 12517 Misses 1564 1564 ```

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[ricab]

Yeah, oops indeed... good thing it doesn't go in releases :disappointed_relieved:

Thanks for the review! :)