This line 635 and 638 of build.sh:

            if [ -f /etc/slackware-release ] || [ -f /etc/slackware-version ]; then
                export WRE_OSTYPE="Slackware"
            fi
            if [ -f /etc/debian_release ] || [ -f /etc/debian_version ]; then
                export WRE_OSTYPE="Debian"
 

Gives this error:

./build.sh: line 635: [: missing `]'
./build.sh: line 635: -f: command not found
./build.sh: line 638: [: missing `]'
./build.sh: line 638: -f: command not found
 

And should be rewritten to this:
            if [ -f /etc/slackware-release ] || [ -f /etc/slackware-version ]; then
                export WRE_OSTYPE="Slackware"
            fi
            if [ -f /etc/debian_release ] || [ -f /etc/debian_version ]; then
                export WRE_OSTYPE="Debian"

Is WRE_OSTYPE (for Slackware or Debian) used anywhere?