A fellow colleague was having some problems with the vCenter Server Appliance (VCSA) CLI Installer when using the vSAN ESA (Express Storage Architecture) bootstrap method, which automatically the configures vSAN ESA on a physical ESXi host before deploying the VCSA on top of the vSAN ESA Datastore.
Whether he manually downloaded the vSAN JSON HCL or generated his own custom vSAN ESA HCL, the VCSA Installer would fail with the following error:
Expecting value: line 1 column 1 (char 0)