Problem Builder - AttributeError: 'NoneType' object has no attribute 'render'

Description

Not sure if this is the right place to fill this bug, let me know if not. Problem Builder is throwing the following error on one of the Davidson courses on edx.org (reported by on HipChat):

This appears in https://courses.edx.org/courses/course-v1:DavidsonNext+Mac_APccx+2T2015/courseware/Classical_and_Keynesian_Models/Let_s_See_What_You_ve_Learned_0/ (you will need to subscribe to the course first at https://www.edx.org/course/apr-macroeconomics-challenging-concepts-davidson-next-macapccx ).

It only seem to show up when the unit is viewed from a student account (or a staff masquerading a student) in the LMS.

Steps to Reproduce

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Current Behavior

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Expected Behavior

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Reason for Variance

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Release Notes

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User Impact Summary

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Assignee

Braden MacDonald

Reporter

Xavier Antoviaque

Labels

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Impact

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Customer

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Partner Manager

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URL

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Groups with Read-Only Access

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Actual Points

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Category of Work

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Platform Map Area (Levels 1 & 2)

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Platform Map Area (Levels 3 & 4)

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Priority

CAT-2
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