Refactoring: Split shared types into seperate modules and document alot.

server/shared/utils/enums.ts

@@ -0,0 +1,30 @@
+/**
+ * Utility functions for enums.
+ */
+
+/**
+ * Helper function to detect unhandled enum fields in `switch` statements at compile time. In case this function
+ * is called at runtime anyway (which should not happen) it throws a runtime error.
+ *
+ * In the example below the compiler will complain if not for all fields of `Enum` a corresponding `case` statement
+ * exists.
+ *
+ * @param field - Unhandled field, the value being switched over.
+ * @throws {@link Error} - If the function is called at runtime.
+ *
+ * @example
+ * switch (enumValue) {
+ *     case Enum.FIELD1:
+ *         return;
+ *     case Enum.FIELD2:
+ *         return;
+ *
+ *     ...
+ *
+ *     default:
+ *         return unhandledEnumField(enumValue);
+ * }
+ */
+export function unhandledEnumField(field: never): never {
+    throw new Error(`Unhandled enum field: ${field}`);
+}