Yes - we have a custom child theme based on MH Magazines Lite that we paid a developer to make for us so I really don't want to choose a different one.
However, for testing, I changed it to MH Magazines Lite - same error.
I changed it to X theme - same error.
I then downloaded and activated theme twenty seventeen as this is a "base" wordpress theme - same error.
I put my child theme back active so that visitors see my site.