Flawed ports's build process created the library that is linked to non-existent dynamic library:
> # ldd -a work/stage//usr/local/lib/lv2/convo.lv2/convoLV2.so
> libzita-convolver.so.3 => not found (0)
Currently, proxydeps misses such situation. I made it to print an error message in such case.
Sorry, please disregard the previous reviews link.
The correct link: https://reviews.freebsd.org/D11837