Weird errors on alternative build

[shakfu]

In my fork, I've moved things around a bit to enable a regular Max package type build with max-sdk-base as a submodule.

On my first attempt to compile, I got the following error:

~/src/scheme-for-max/source/projects/s4m/s4m-grid.c:302:60: error: cannot take the address of an rvalue of type 't_object *' (aka 'struct object *')
    t_max_err err = hashtab_lookup(s4m_arrays, array_name, &(t_object *)array);
                                                           ^~~~~~~~~~~~~~~~~~

I think this is a valid error, it should be (consistent with this similar case):

    t_max_err err = hashtab_lookup(s4m_arrays, array_name, (t_object **)&array);

If the above is fixed, then I get a bunch of errors and even more warnings (which are omitted to reduce the noise):

                             ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2087:56: error: cannot take the address of an rvalue of type 't_object *' (aka 'struct object *')
        hashtab_lookup(s4m_arrays, gensym(array_name), &(t_object *)array);
                                                       ^~~~~~~~~~~~~~~~~~
// ... (lots of warnings)
                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2316:9: error: void function 's4m_bang' should not return a value [-Wreturn-type]
        return defer(x, s4m_callback_bang, NULL, 1, ap);
        ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// ... (lots of warnings)
                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2360:9: error: void function 's4m_int' should not return a value [-Wreturn-type]
        return defer(x, s4m_callback_int, NULL, 2, ap);
        ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


~/src/scheme-for-max/source/projects/s4m/s4m.c:2427:9: error: void function 's4m_float' should not return a value [-Wreturn-type]
        return defer(x, s4m_callback_float, NULL, 2, ap);
        ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2508:13: error: void function 's4m_list' should not return a value [-Wreturn-type]
            return defer(x, s4m_callback_list, s, argc + 1, ap);
            ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2584:9: error: void function 's4m_eval_string' should not return a value [-Wreturn-type]
        return defer(x, s4m_s7_eval_string, s, 0, NULL);
        ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2816:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_0, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2818:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_1, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2820:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_2, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2822:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_3, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2824:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_4, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
~/src/scheme-for-max/source/projects/s4m/s4m.c:2826:17: error: void function 's4m_msg' should not return a value [-Wreturn-type]
                return defer(x, s4m_callback_msg_inlet_5, s, argc, argv);
                ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                            ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
133 warnings and 20 errors generated.
make[3]: *** [source/projects/s4m/CMakeFiles/s4m.dir/s4m.c.o] Error 1
make[2]: *** [source/projects/s4m/CMakeFiles/s4m.dir/all] Error 2
make[1]: *** [all] Error 2
make: *** [build] Error 2

The first of this batch is similar to the initial error and easily fixable but the others, well it looks like there's a general pattern of widely using return defer(..) and return schedule(...) in void functions.

Do you have any insight about what may be the issue here?