Warning when deleting queued portfolio

Mahara master 15.10 (potentially also 15.04)

Admin -> Users -> Export queue

When I delete a queued export, I get:

[WAR] 46 (admin/users/exportqueue.php:63) Invalid argument supplied for foreach()
Call stack (most recent first):

    log_message("Invalid argument supplied for foreach()", 8, true, true, "/home/kristina/code/mahara/htdocs/admin/users/expo...", 63) at /home/kristina/code/mahara/htdocs/lib/errors.php:441
    error(2, "Invalid argument supplied for foreach()", "/home/kristina/code/mahara/htdocs/admin/users/expo...", 63, array(size 68)) at /home/kristina/code/mahara/htdocs/admin/users/exportqueue.php:63

[WAR] 46 (admin/users/exportqueue.php:78) Trying to get property of non-object
Call stack (most recent first):

    log_message("Trying to get property of non-object", 8, true, true, "/home/kristina/code/mahara/htdocs/admin/users/expo...", 78) at /home/kristina/code/mahara/htdocs/lib/errors.php:441
    error(8, "Trying to get property of non-object", "/home/kristina/code/mahara/htdocs/admin/users/expo...", 78, array(size 68)) at /home/kristina/code/mahara/htdocs/admin/users/exportqueue.php:78

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For the export queue to work, you'd need to turn on "Export to queue" in Config site -> User settings and export a portfolio as Leap2A file.