That’s what I thought was happening. You’ve installed to a path with a space in it.
This thread deals with the same bug. We’ve fixed it in 3.7.0-beta2; alternatively, if you don’t want to install 3.7.0-beta2, you can edit the VASSAL.sh you have by changing this line
INSTALL_DIR=$(dirname ${EXEC_PATH})
to
INSTALL_DIR=$(dirname "${EXEC_PATH}")