Hi Hans,

in the old loader, defining a feature containing mixed ligature /
substitution causes a crash. Here’s an example:

    \enabletrackers [otf.loading]
    \startluacode
      fonts.handlers.otf.addfeature ("dunno", {
          {
              type      = "substitution",
              data      = { [0x0022] = 0x201D },
              prepend   = true,
          },
          {
              type     = "ligature",
              data     = { [0x2013] = {0x002D, 0x002D} },
              prepend  = true,
          },
      })
      fonts.handlers.otf.features.register {
          name        = "dunno",
          description = "bug demo",
      }
    \stopluacode

    \definefontfeature [myfeat] [default] [dunno=yes,liga=yes,mode=node]

    \definefont [somefont] [file:cmunrm.otf*myfeat]
    \starttext
      \somefont foo bar " baz
    \stoptext

This crashes in font-otn on account of a number being indexed.
This used to work -- anything that can be done about it?

Best,
Philipp