The relevant first error in your log is:
:info:build healpy/src/_healpy_pixel_lib.cc:400:3: error: address of overloaded function 'ufunc_ang2pix' does not match required type 'void (char **, const long *, const long *, void *)'
:info:build ufunc_ang2pix<RING>
:info:build ^~~~~~~~~~~~~~~~~~~
:info:build healpy/src/_healpy_pixel_lib.cc:42:3: note: candidate template ignored: could not match 'void (char **, npy_intp *, npy_intp *, void *)' (aka 'void (char **, long *, long *, void *)') against 'void (char **, const long *, const long *, void *)'
:info:build ufunc_ang2pix(char **args, npy_intp *dimensions, npy_intp *steps, void *func)
:info:build ^
I see the same build failure. Maybe the update of py-numpy to 1.19.0 last month broke py-healpy. It doesn't sound like a MacPorts-specific problem so you could look in the upstream issue tracker and file a ticket there if they don't already have one for this problem.
