remove UnknownError

Author: liam-teale

include/common/result.hpp

@@ -41,20 +41,6 @@ class ResultError {
     std::optional<RuntimeData> runtime_data;
 };
 
-/**
- * @brief Unknown Error
- *
- */
-class UnknownError : public ResultError {
-  public:
-    template<typename T>
-        requires std::convertible_to<T, std::string>
-    UnknownError(T&& message)
-        : message(std::forward<T>(message)) {}
-
-    std::string message;
-};
-
 /**
  * @brief Trait to define a "sentinel" value for types indicating an error state.
  * @tparam T Type to provide a sentinel value for.