My package.json lists:
If I go to the console, and run node --version, I get back v6.11.2. I expected it to output 8.4.0.
The console runs a different node version (but it can be changed with nvm use X). The version of node your project is using gets outputted to the logs during the installation phase, so that’s where you can tell if it’s picking up your package.json settings or not.
nvm use X