fix(theming): Fix imagick segmentation fault when rendering an app icon

[provokateurin]

Since a few months my imagick happily segfaults on the drawImage in the next line, taking down the entire web server. I have no idea why this change fixes it, but it does 🤷‍♀️

[provokateurin]

/backport to stable35

[provokateurin]

/backport to stable34

[provokateurin]

/backport to stable33

[icewind1991]

Is $size 0/1 sometimes by any chance?

[provokateurin]

I just checked and in all requests I observed it was 512.

[provokateurin]

The tests for this stuff are pretty bad, because they just have the same code to generate the icon and compare it 😭

[backportbot]

The backport to stable33 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable33
git pull origin stable33

# Create the new backport branch
git checkout -b backport/64955/stable33

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 34774afd

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/64955/stable33

Error: Failed to check for changes with origin/stable33: No changes found in backport branch

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[provokateurin]

stable33 doesn't have the same issue, so no backport needed.