fix: check if properties exist before using them

[SebastianKrupinski]

Resolves:

Error: Call to a member function getValue() on null
#6 /var/www/nextcloud/lib/private/Calendar/Manager.php(333): OC\Calendar\Manager::handleIMipReply
#5 /mail/lib/Service/IMipService.php(149): OCA\Mail\Service\IMipService::process
#4 /mail/lib/BackgroundJob/IMipMessageJob.php(29): OCA\Mail\BackgroundJob\IMipMessageJob::run
#3 /var/www/nextcloud/lib/public/BackgroundJob/Job.php(61): OCP\BackgroundJob\Job::start
#2 /var/www/nextcloud/lib/public/BackgroundJob/TimedJob.php(97): OCP\BackgroundJob\TimedJob::start
#1 /var/www/nextcloud/lib/public/BackgroundJob/TimedJob.php(84): OCP\BackgroundJob\TimedJob::execute
#0 /var/www/nextcloud/cron.php(170): null

Summary

• Added addition check to make sure properties exist
• Added addition test

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[SebastianKrupinski]

/backport to 31

[ChristophWurst]

🐘

[backportbot]

The backport to 31 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout 31
git pull origin 31

# Create the new backport branch
git checkout -b backport/52778/31

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick ebd80bc1

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/52778/31

Error: Failed to clone repository: Failed to create working tree: Preparing worktree (new branch 'backport/52778/31')
fatal: not a valid object name: 'origin/31'

---

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

[ChristophWurst]

/backport to stable31

[SebastianKrupinski]

When you miss type the branch name in the backport commad 🫏 🫏

[solracsf]

Is it possible to backport this PR to 30?

[st3iny]

Is it possible to backport this PR to 30?

@SebastianKrupinski Is there a reason for not backporting further, for example, the fixed code is missing on stable30?

[SebastianKrupinski]

/backport to stable30

[SebastianKrupinski]

@SebastianKrupinski Is there a reason for not backporting further, for example, the fixed code is missing on stable30?

There was a reason, but I don't remember the reason now, I'll backport it this morning.