Fix clang global vars nil value (#215)

lua/nv-globals.lua

@@ -52,6 +52,9 @@ O = {
     },
     tailwindls = {
         filetypes = {'html', 'css', 'scss', 'javascript', 'javascriptreact', 'typescript', 'typescriptreact'}
+    },
+    clang = {
+        diagnostics = {virtual_text = true, signs = true, underline = true}
     }
     -- css = {formatter = '', autoformat = false, virtual_text = true},
     -- json = {formatter = '', autoformat = false, virtual_text = true}