Error: Add error codes to ErrorOr<> and add constructors

This allows us to handle functions that can fail in multiple different ways

src/lib/error.h++

@@ -15,22 +15,59 @@
 
 #pragma once
 
+#include <cstdint>
+
 template <typename T>
 struct ErrorOr {
     bool isError;
+    uint8_t errorCode;
     T value;
 
     ErrorOr<T>();
     ErrorOr<T>(T);
+    ErrorOr<T>(bool);
+    ErrorOr<T>(bool, uint8_t);
+    ErrorOr<T>(bool, uint8_t, T);
 };
 
 template <typename T>
 ErrorOr<T>::ErrorOr() {
     this->isError = false;
+    this->errorCode = 0;
 }
 
 template <typename T>
 ErrorOr<T>::ErrorOr(T value) {
     this->isError = false;
+    this->errorCode = 0;
     this->value = value;
 }
+
+template <typename T>
+ErrorOr<T>::ErrorOr(bool isError) {
+    this->isError = isError;
+    this->errorCode = 0;
+}
+
+template <typename T>
+ErrorOr<T>::ErrorOr(bool isError, uint8_t errorCode) {
+    this->isError = isError;
+    this->errorCode = errorCode;
+}
+
+template <typename T>
+ErrorOr<T>::ErrorOr(bool isError, uint8_t errorCode, T value) {
+    this->isError = isError;
+    this->errorCode = errorCode;
+    this->value = value;
+}
+
+namespace ErrorCodes {
+    // These are all arbitrary values used to assign error codes to different
+    // kinds of errors.
+    // Using them is optional as ErrorOr<> accepts any uint8_t value as
+    // error code, but they are useful for readability.
+
+    // IndexOutOfRangeException equivalent
+    const uint8_t RANGE_ERROR = 1;
+}