Update modUser.php

[BobRay]

Prevent PHP error when $_SESSION is not set (e.g., in a unit or acceptance test).

What does it do?

Sanity check for $_SESSION

Why is it needed?

Original code throws a PHP fatal error if $_SESSION is not set.

How to test

Related issue(s)/PR(s)

Issue: #15374

[cla-bot]

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[BobRay]

@cla-bot check

…

On Sat, Feb 6, 2021 at 4:15 PM cla-bot[bot] ***@***.***> wrote: Thank you for your contribution! Before your pull request can be reviewed, please sign the MODX Contributor License Agreement (CLA) <https://modx.com/community/contribute/cla/>. This is to make sure MODX has your written permission to distribute projects containing your contributions under the appropriate license. Please make sure the CLA has been signed for GitHub user(s): @BobRay <https://github.com/BobRay> Once you've signed, please reply with @cla-bot check to verify and update the status of this pull request. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#15376 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACRZIS3YLIATP6TZLHAREDS5WWPXANCNFSM4XGVQ4RQ> .

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!