I have a number of docs that have processed properly until the latest beta. Now I get this complaint in each very early in the processing: 

lua error       > lua error on line 39 in file xxxxxxx:

...eXt/tex/texmf-context/tex/context/base/mkiv/strc-not.lua:324: attempt to index field '' (a nil value)

stack traceback:

...eXt/tex/texmf-context/tex/context/base/mkiv/strc-not.lua:324: in function 'action1'

[string "..."]:6: in function <[string "..."]:5>

(...tail calls...)

Is this a bug or has there been some change in ConTeXt coding that I need to address?

Alan