VMWare Fusion Error - The file system on which your virtual machine resides is critically low on free space.

To resolve this issue on a Macintosh host machine:

1. Shut down the operating system within the Virtual Machine
2. Suspend the Virtual Machine (using the pause button)
3. Go to Virtual Machine > Settings > General
4. Click on the "Clean Up Virtual Machine" button

Note: if the button is greyed out, double-check that you have actually shut down the virtual machine's operating system, not just suspended the VM.