node wants to use the "Local Items" keychain
I got this too, and I ran "ps aux | grep node" from the terminal. I've seen a couple of different programs show up. One was Videostream. Another was actually Adobe Creative Cloud:

kenlu              693   0.0  0.2  5996836  27612   ??  S    11Dec18  23:09.26 /Applications/Utilities/Adobe Creative Cloud Experience/CCXProcess/CCXProcess.app/Contents/MacOS/../libs/node /Applications/Utilities/Adobe Creative Cloud Experience/CCXProcess/CCXProcess.app/Contents/MacOS/../js/main.js

So it looks like this is just part of Adobe Creative Cloud, which is probably fine.