Add better logging for when the lazyContext is missing

Hello @majelbstoat, 

Please review the following commits I made in branch 'nick-errors2'.

588dcea6761ae06e47e2fc830defe729a5f52f59 (2013-12-03 12:34:19 -0500)
Add better logging for when the lazyContext is missing

R=@majelbstoat