Looks like, so many packages are outdated.
package node-sass is creating the issue.

`1 error generated.
make: *** [Release/obj.target/binding/src/create_string.o] Error 1

gyp ERR! build error
gyp ERR! stack Error: make failed with exit code: 2
gyp ERR! stack at ChildProcess.onExit (/Volumes/gitdisk/code/sites/spree-on-react/node_modules/node-gyp/lib/build.js:262:23)
gyp ERR! stack at ChildProcess.emit (events.js:200:13)
gyp ERR! stack at Process.ChildProcess._handle.onexit (internal/child_process.js:272:12)
gyp ERR! System Darwin 18.7.0
gyp ERR! command "/usr/local/Cellar/node/12.3.1/bin/node" "/Volumes/gitdisk/code/sites/spree-on-react/node_modules/node-gyp/bin/node-gyp.js" "rebuild" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--libsass_library="
gyp ERR! cwd /Volumes/gitdisk/code/sites/spree-on-react/node_modules/node-sass
gyp ERR! node -v v12.3.1
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok
Build failed with error code: 1
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] postinstall: node scripts/build.js
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] postinstall script.`