NPE when accessing a Forum from Lessons

A user gets an NPE when trying to access a forum from the Lessons page.  To reproduce:

-Create a new site

-Add Lessons and Forums tools

-Go into Forums, click General Discussion and Start a New Conversion

-Enter Title and Message, then click Post

-Go into Lessons, and click Add Content

-Choose "Link to a forum or topic"

-Click "Use Selected Item" (it will default to the forum topic added above)

-On the Lessons page, click the link that was just created.  

-Bug report for NPE will appear

See attached stack trace.