Error message:

tsserver_provider.lua:67: attempt to call field 'sanitize' (a nil value) 

Here is where it's being called:

The commit removing it:

neovim/nvim-lspconfig@d651732#diff-9e30880c16142e9d50a64563fd1260aa9f851b782dd74678163e151b93878568L219

It seems lspconfig still has a utils.sanitize, but it's deprecated in favor of vim.fs.normalize which appears to be a drop-in replacement.