Homebridge

For some reason, after upgrading to 18.04, npm wasn't installed and the default npm install location was /usr/local/lib/node_modules rather than /usr/lib/node_modules (which it seems to have been before 18.04).

To fix errors like:

Jan 17 23:52:38 maine homebridge[13898]: Error: The module '/usr/lib/node_modules/homebridge/node_modules/mdns/build/Release/dns_sd_bindings.node'
Jan 17 23:52:38 maine homebridge[13898]: was compiled against a different Node.js version using
Jan 17 23:52:38 maine homebridge[13898]: NODE_MODULE_VERSION 48. This version of Node.js requires
Jan 17 23:52:38 maine homebridge[13898]: NODE_MODULE_VERSION 57. Please try re-compiling or re-installing
Jan 17 23:52:38 maine homebridge[13898]: the module (for instance, using `npm rebuild` or `npm install`).

- cd to /usr/lib/node_modules - run `sudo npm rebuild homebridge`