Can't launch Finder window from terminal on Mojave

Not able to reproduce the error as I have access to Catalina's and High Sierra's macs but not Mojave. But you may want to try if updating permissions for your Terminal.app and iTerm.app resolved the issue:

System Preferences> Security&Privacy> Privacy> add both apps to "Accessibility" and "Automation" lists

Deleting & re-adding them could also help (it worked for me a few weeks back, re-enabling osascript assistive access to the system UI for my terminal scripts that had suddenly stopped working).

Nota & Disclaimer: control panel headings above are Catalina's - High Sierra has only "Accessibility" - Mojave's should be close enough though -- Obviously changing any such Security settings is done at your own risks etc... -- while I did not have to do it in my case, logoff/logon could help ensure the permissions are properly applied.