When I launch terminal I am getting the following message that was not there before:
N/A: version "N/A" is not yet installed.
You need to run "nvm install N/A" to install it before using it.
I am using zsh as my shell and I have nvm configured properly from the install instructions and loading it in my zshrc file.
The message is erroneously telling you to install a version of Node that doesn't exist, because you probably recently updated node and forgot to let nvm know to use it as the new default. To remove the message do the following:
nvm ls and take note of the N/A version that is default and the versions available
nvm alias default v(whatever version you have updated to) e.g. nvm alias default v10.15 in my case.
The next time you load the shell the message should be gone.