logging: Fix log filter during initialization

The log filter was being ignored on initialization due to the logging instance being initialized before the config instance, so the log filter was set to its default value.

This fixes that oversight, along with using descriptive exceptions instead of abort() calls.

src/core/core.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <exception>
 #include <memory>
 #include <stdexcept>
 #include <utility>
@@ -68,9 +69,16 @@ Core::Timing& Global() {
 
 System::~System() = default;
 
+System& System::GetInstance() {
+    if (!s_instance) {
+        throw std::runtime_error("Using System instance before its initialization");
+    }
+    return *s_instance;
+}
+
 void System::InitializeGlobalInstance() {
     if (s_instance) {
-        std::abort();
+        throw std::runtime_error("Reinitializing Global System instance.");
     }
     s_instance = std::unique_ptr<System>(new System);
 }

src/core/core.h

@@ -73,12 +73,7 @@ public:
      * Gets the instance of the System singleton class.
      * @returns Reference to the instance of the System singleton class.
      */
-    [[nodiscard]] static System& GetInstance() {
-        if (!s_instance) {
-            std::abort();
-        }
-        return *s_instance;
-    }
+    [[nodiscard]] static System& GetInstance();
 
     static void InitializeGlobalInstance();