test case:
class xyz {
  void func () { }

  void a (GLib.Object obj) {
    Signal.connect (obj, "my_signal", func, null);
  }
}


fails with this assertion:
ERROR:arraylist.c:177:gee_array_list_real_get: assertion failed: (_tmp0)

which is really an access-out-of-bounds-index-in-array error.  backtrace includes:

+ Trace 214086

and the region in the .vala code responsible:

  if (m.binding == MemberBinding.INSTANCE) {
    CCodeExpression arg;
    if (d.has_target) {
      arg = new CCodeIdentifier ("self");
    } else {
      // use first delegate parameter as instance
      arg = new CCodeIdentifier ((d_params.get (0).ccodenode as
                                  CCodeFormalParameter).name);

problem, of course, is that the func() function doesn't have a parameter #0.