ocaml-dumpast failure not observed

[dsheets]

dsheets@thinkxen:~/Code/webmaster$ ocaml-dumpast camlp4o  _build/lib-webmaster/urlfun.ml > _build/lib-webmaster/urlfun.cml-byte
File "_build/lib-webmaster/urlfun.ml", line 91, characters 2-6:
Error: Syntax error
dsheets@thinkxen:~/Code/webmaster$ echo $?
2

but

ocaml-dumpast camlp4o  _build/lib-webmaster/urlfun.ml > _build/lib-webmaster/urlfun.cml-byte
File "_build/lib-webmaster/urlfun.ml", line 91, characters 2-6:
Error: Syntax error
ocamldep.opt  -I _build/lib-webmaster -impl _build/lib-webmaster/urlfun.cml-byte > _build/lib-webmaster/urlfun.ml.d
ocamlc.opt -c  -g -bin-annot -I _build/lib-webmaster -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/netsys -I /home/dsheets/.opam/4.01.0+fp/lib/netstring -I /home/dsheets/.opam/4.01.0+fp/lib/xmlm -I /home/dsheets/.opam/4.01.0+fp/lib/re -I /home/dsheets/.opam/4.01.0+fp/lib/re -I /home/dsheets/.opam/4.01.0+fp/lib/stringext -I /home/dsheets/.opam/4.01.0+fp/lib/sexplib -I /home/dsheets/.opam/4.01.0+fp/lib/uri -intf _build/lib-webmaster/urlfun.cmli-byte
ocamlc.opt -c  -g -bin-annot -I _build/lib-webmaster -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/ocaml -I /home/dsheets/.opam/4.01.0+fp/lib/netsys -I /home/dsheets/.opam/4.01.0+fp/lib/netstring -I /home/dsheets/.opam/4.01.0+fp/lib/xmlm -I /home/dsheets/.opam/4.01.0+fp/lib/re -I /home/dsheets/.opam/4.01.0+fp/lib/re -I /home/dsheets/.opam/4.01.0+fp/lib/stringext -I /home/dsheets/.opam/4.01.0+fp/lib/sexplib -I /home/dsheets/.opam/4.01.0+fp/lib/uri -impl _build/lib-webmaster/urlfun.cml-byte
File "_build/lib-webmaster/urlfun.cml-byte", line 1:
Error: The implementation _build/lib-webmaster/urlfun.cml-byte
       does not match the interface _build/lib-webmaster/urlfun.cmi:
       The field `revert_path' is required but not provided
       The field `remove_common_prefix' is required but not provided
       The field `map_file' is required but not provided
       The field `map_css_file' is required but not provided
       The field `map_html_file' is required but not provided
       The field `map_html_element_hrefs' is required but not provided
       The field `map_html_hrefs' is required but not provided
       The field `Unknown_file_type' is required but not provided
Makefile:472: recipe for target '_build/lib-webmaster/urlfun.cmo' failed
make[1]: *** [_build/lib-webmaster/urlfun.cmo] Error 2
make[1]: Leaving directory '/home/dsheets/Code/webmaster'
Makefile:249: recipe for target 'all' failed
make: *** [all] Error 2

[samoht]

Any idea how to fix this (ie. avoiding the generation of an empty file if the command fail) ?

[dsheets]

Working on it.