make_opt_error.m:019: Error: clause for automatically generated field access
make_opt_error.m:019:   function `x'/1.
make_opt_error.m:019:   Clauses for field access functions are automatically
make_opt_error.m:019:   generated by the compiler. To supply your own
make_opt_error.m:019:   definition for a field access function, for example to
make_opt_error.m:019:   check the input to a field update, give the field of
make_opt_error.m:019:   the constructor a different name.
make_opt_error.m:020: Error: clause for automatically generated field access
make_opt_error.m:020:   function `y'/1.
make_opt_error.m:020:   Clauses for field access functions are automatically
make_opt_error.m:020:   generated by the compiler. To supply your own
make_opt_error.m:020:   definition for a field access function, for example to
make_opt_error.m:020:   check the input to a field update, give the field of
make_opt_error.m:020:   the constructor a different name.