code: function checkForDisallowedESSymbolOperand(operator) {
                  var offendingSymbolOperand = maybeTypeOfKind(leftType, 512 /* ESSymbol */) ? left :
                      maybeTypeOfKind(rightType, 512 /* ESSymbol */) ? right :
                          undefined;
                  if (offendingSymbolOperand) {
                      error(offendingSymbolOperand, ts.Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, ts.tokenToString(operator));
                      return false;
                  }
                  return true;
              }
docs: Return true if there was no error, false if there was an error.