npm needs run

binder/postBuild

@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
 set -eux
 npm install
-npm build
+npm run build
 npm pack
 jupyter labextension install ./jupyterlab-drawio-*.tgz --no-build --debug
 jupyter lab build --dev-build=False --minimize=True --debug
+jupyter labextension list