add Serenity-style ErrorOr<> type

src/lib/error.cpp

@@ -0,0 +1 @@
+#include "error.h++"

src/lib/error.h++

@@ -0,0 +1,21 @@
+#pragma once
+
+template <typename T>
+struct ErrorOr {
+    bool isError;
+    T value;
+
+    ErrorOr<T>();
+    ErrorOr<T>(T);
+};
+
+template <typename T>
+ErrorOr<T>::ErrorOr() {
+    this->isError = false;
+}
+
+template <typename T>
+ErrorOr<T>::ErrorOr(T value) {
+    this->isError = false;
+    this->value = value;
+}