Hey list,

2013.09.18 appears to be broken. When typesetting my book, I receive the
following fatal error...

        ! LuaTeX error /usr/share/texmf/tex/context/base/font-syn.lua:596: bad argument #2 to 'f_a' (number expected, got string) stack traceback:
        [C]: in function 'f_a'
                /usr/share/texmf/tex/context/base/font-syn.lua:596: in function 'collectstatistics'
                /usr/share/texmf/tex/context/base/font-syn.lua:1071: in function 'identify'
                /usr/share/texmf/tex/context/base/font-syn.lua:1089: in function 'load'
                /usr/share/texmf/tex/context/base/font-syn.lua:1100: in function 'load'
                /usr/share/texmf/tex/context/base/font-syn.lua:1259: in function 'resolvedspecification'
                /usr/share/texmf/tex/context/base/font-syn.lua:1269: in function 'resolve'
                /usr/share/texmf/tex/context/base/font-syn.lua:1678: in function 'exists'
                ...re/texmf/tex/context/third/simplefonts/t-simplefonts.lua:182: in function 'selectfont'
                [string "\directlua "]:1: in main chunk.
        \syst_helpers_comma_list_step ...ter \c!weight ")}
                                                          
        \9>>1 #1,e-\syst_helpers_comma_list_step {#1}
                                                     \syst_helpers_do_process_comma_...
        <argument> \relax regular,
                       italic,slanted,bold,bolditalic,boldslanted,caps, italiccaps,slan
        \syst_helpers_do_process_comma_list ...argument #1
                                                          ,]\relax \global \advance ...
        \simplefonts@definetextfont ...rocesscommacommand 
                                                          \ifx \currenttypeface \v!s...
        \syst_helpers_quadruple_empty_four_spaced ...4}][]
                                                           
        ...
        l.397     \setupbodyfont[11pt]

It looks as though the problem is buried in line 596 of font-syn.lua.
For some reason s.angle is typed as a Lua string and not a number.

        local angle   = f_a(s.angle or 0)

-- 
Kip Warner -- Software Engineer
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http://www.thevertigo.com