Fix: #496 NPM_FLAGS doesn't handle more than one flag (#590)

Co-authored-by: Celine Pelletier <cpelletier@ferlab.bio>

Author: JGAntunes

run-build-functions.sh

@@ -185,7 +185,7 @@ run_npm() {
   then
     echo "Installing NPM modules using NPM version $(npm --version)"
     run_npm_set_temp
-    if npm install ${NPM_FLAGS:+"$NPM_FLAGS"}
+    if npm install ${NPM_FLAGS:+$NPM_FLAGS}
     then
       echo "NPM modules installed"
     else