So this is likely affecting lots of NiM users but there is a quick and easy workaround until the problem is fixed upstream. The fix...
Open DevTools manually with the keyboard shortcut
F12 or Control+Shift+I on Linux/Windows or
Command+Option+I on Mac.
Read more about the bug here: https://bugs.chromium.org/p/chromium/issues/detail?id=900945&q=ERR_INVALID_URL&can=2