Update builder/src/build.ts
Update builder/src/build.ts

Co-authored-by: Jason Grout <b4672d8584c95d3dfb8fbf3ae0597a23208547c6@users.noreply.github.com>
jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab