"An error occurred installing macOS" in VMware?
After some more tinkering, I realized that packer was supplying a sloppy configuration to VMware Fusion, compared to how VMware Fusion prefers to configure macOS VM's. When I create the VM by using the VMware Fusion wizard rather than with packer, then the VM installs and boots successfully. Here is my working VMX configuration for posterity:

https://gist.github.com/mcandre/48f90963d9a24315024319cd62142f6a