/usr/bin/objdump is provided by obsolete GNU binutils 2.17.50, and is expectd to be removed by FreeBSD 13.0. The www/node* packages are one of three groups that failed in an exp-run.
Node.js compile error: could not find objdump
Check that GNU binutils are installed and included in PATH
Most likely www/node* should just depend on devel/binutils if it needs objdump.