[luatex] Prevent stop when tiff file loads

[Patrick Gundlach]

Hello all,

I am using LuaTeX 0.79.1 and use

    local foo = img.scan({filename = "foo.tiff"})

but this fails with 

!LuaTeX error: internal error: unknown image type (2)
 ==> Fatal error occurred, no output PDF file produced!


Is there a way to prevent LuaTeX from stopping the whole process? Is there a 
function like 

can_you_handle_this_imagetype(filename="foo.tiff")

?


Patrick