code: function reportObviousModifierErrors(node) {
              return !node.modifiers
                  ? false
                  : shouldReportBadModifier(node)
                      ? grammarErrorOnFirstToken(node, ts.Diagnostics.Modifiers_cannot_appear_here)
                      : undefined;
          }
docs: true | false: Early return this value from checkGrammarModifiers.
  undefined: Need to do full checking on the modifiers.