You can fix the mode of the file by running
chmod 4755 /usr/lib/node_modules/electron/dist/chrome-sandbox
as root (or with `sudo`).
To see the current mode, run
stat /usr/lib/node_modules/electron/dist/chrome-sandbox
and look at the “Access” line — this will show the mode in both octal format (four octal digits as used in the error message) and symbolic format (as used in `ls -l`’s output).