Method convertToErrorCode

ext/include/llvm/Support/JSON.h:701–703

    OS << llvm::formatv("[{0}:{1}, byte={2}]: {3}", Line, Column, Offset, Msg);
  }
  std::error_code convertToErrorCode() const override {
    return llvm::inconvertibleErrorCode();
  }
};

/// json::OStream allows writing well-formed JSON without materializing