Could be a faulty installation…
At the 3rd Party Modules page on GitHub you’ll find 2 different versions of the MMM-GoogleTrafficTimes module; an old one from pjestico and a newer one from Jacopo1891.
I couldn’t get the Jacopo1891 version working, so I tried the pjestico version (on MacOS), and got the following error at installation:
npm ERR! Your cache folder contains root-owned files, due to a bug in
npm ERR! previous versions of npm which has since been addressed.
npm ERR!
npm ERR! To permanently fix this problem, please run:
npm ERR! sudo chown -R 501:20 "/Users/harriev/.npm"
It fixed the problem indeed, the module worked fine afterwards.
Then, I removed the old module, installed the Jacopo1891 version and that
worked as well.