My LOCALBASE is set to /opt, but the port created usr/local under ${STAGEDIR} anyway. The install then failed...
A commit references this bug: Author: mi Date: Fri Jul 13 20:53:28 UTC 2018 New revision: 474607 URL: https://svnweb.freebsd.org/changeset/ports/474607 Log: Explicitly set prefix for install to work on systems, where it is different from /usr/local PR: 228729 Approved by: maintainer timeout Changes: head/lang/spidermonkey52/Makefile
The prefix problem should now be resolved. Other problems with the port: . it is behind times -- 52.8.1 and 52.9.0 are both available at this time . it extracts too much from DISTFILE will be addressed by a future PR.