Missing preview.min.js, breaks the preview #54

Did you forget to check this in?

To view your forest, open http://localhost:8080 in your browser.
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62827
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62828
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62829
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62830
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62831
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62832
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62833
+Server: Eio.Io Fs Not_found Unix_error (No such file or directory, "openat", "/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js"),
+  opening <fs:/Users/jon/.opam/5.4.0/share/forester/themes/default/preview.min.js>,
+  handling connection from tcp:127.0.0.1:62834