[dev-context] Bug in \usepath

[Marco]

There's something fishy with \usepath. A simple call fails with

! LuaTeX error ...-new/tex/texmf-context/tex/context/base/data-res.lua:688: attempt to get length of local 'subpaths' (a nil value)
stack traceback:
	...-new/tex/texmf-context/tex/context/base/data-res.lua:688: in function 'registerextrapath'
	...-new/tex/texmf-context/tex/context/base/file-job.lua:71: in function 'usepath'
	<main ctx instance>:1: in main chunk.

\usepath [chapters]
\starttext
  Foo
\stoptext


Marco