Made some changes from review comments:

- Made LoadKernelSystemMode return a pair consisting of a system mode and a result code (Could use review).
- Deleted ErrorOpenGL error code in favor of just having ErrorVideoCore.
- Made dialog messages more clear.
- Compared archive ID in fs_user.cpp to ArchiveIdCode::NCCH as opposed to hex magic.
- Cleaned up some other stuff.

src/core/loader/loader.h

@@ -8,8 +8,11 @@
 #include <initializer_list>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
+
 #include <boost/optional.hpp>
+
 #include "common/common_types.h"
 #include "common/file_util.h"
 
@@ -100,13 +103,11 @@ public:
      * Loads the system mode that this application needs.
      * This function defaults to 2 (96MB allocated to the application) if it can't read the
      * information.
-     * @param boost::optional<u32> Reference to Boost optional to store system mode.
-     * @ return Result of operation.
+     * @return A pair with the system mode (If found) and the result.
      */
-    virtual ResultStatus LoadKernelSystemMode(boost::optional<u32>& system_mode) {
+    virtual std::pair<boost::optional<u32>, ResultStatus> LoadKernelSystemMode() {
         // 96MB allocated to the application.
-        system_mode = 2;
-        return ResultStatus::Success;
+        return std::make_pair(2, ResultStatus::Success);
     }
 
     /**

src/core/loader/ncch.cpp

@@ -121,19 +121,16 @@ FileType AppLoader_NCCH::IdentifyType(FileUtil::IOFile& file) {
     return FileType::Error;
 }
 
-ResultStatus AppLoader_NCCH::LoadKernelSystemMode(boost::optional<u32>& system_mode) {
+std::pair<boost::optional<u32>, ResultStatus> AppLoader_NCCH::LoadKernelSystemMode() {
     if (!is_loaded) {
         ResultStatus res = LoadExeFS();
         if (res != ResultStatus::Success) {
-            // Set the system mode as invalid.
-            system_mode = boost::none;
-            // Return the error code.
-            return res;
+            return std::make_pair(boost::none, res);
         }
     }
     // Set the system mode as the one from the exheader.
-    system_mode = exheader_header.arm11_system_local_caps.system_mode.Value();
-    return ResultStatus::Success;
+    return std::make_pair(exheader_header.arm11_system_local_caps.system_mode.Value(),
+                          ResultStatus::Success);
 }
 
 ResultStatus AppLoader_NCCH::LoadExec() {

src/core/loader/ncch.h

@@ -179,10 +179,9 @@ public:
 
     /**
      * Loads the Exheader and returns the system mode for this application.
-     * @param boost::optional<u32> Reference to Boost optional to store system mode.
-     * @return Result of operation.
+     * @return A pair with the system mode (If found) and the result.
      */
-    ResultStatus LoadKernelSystemMode(boost::optional<u32>& system_mode) override;
+    std::pair<boost::optional<u32>, ResultStatus> LoadKernelSystemMode() override;
 
     ResultStatus ReadCode(std::vector<u8>& buffer) override;