MemoryCard: Defer creation of card until first save

Also do not overwrite the card if it failed to load.

src/core/memory_card.cpp

@@ -302,17 +302,23 @@ std::unique_ptr<MemoryCard> MemoryCard::Open(std::string_view filename)
   if (!FileSystem::FileExists(mc->m_filename.c_str())) [[unlikely]]
   {
     Host::AddIconOSDMessage(fmt::format("memory_card_{}", filename), ICON_FA_SD_CARD,
-                            fmt::format(TRANSLATE_FS("OSDMessage", "Memory card '{}' does not exist, creating."),
-                                        Path::GetFileName(filename), Host::OSD_INFO_DURATION));
+                            fmt::format(TRANSLATE_FS("MemoryCard", "{} does not exist, using empty memory card."),
+                                        Path::GetFileName(filename)),
+                            Host::OSD_INFO_DURATION);
     mc->Format();
-    mc->SaveIfChanged(true);
+    mc->m_changed = false;
   }
   else if (!MemoryCardImage::LoadFromFile(&mc->m_data, mc->m_filename.c_str(), &error)) [[unlikely]]
   {
-    Host::AddIconOSDMessage(fmt::format("memory_card_{}", filename), ICON_FA_SD_CARD,
-                            fmt::format(TRANSLATE_FS("OSDMessage", "Memory card '{}' could not be read: {}"),
-                                        Path::GetFileName(filename), Host::OSD_INFO_DURATION));
+    Host::AddIconOSDMessage(
+      fmt::format("memory_card_{}", filename), ICON_FA_SD_CARD,
+      fmt::format(TRANSLATE_FS("MemoryCard", "{} could not be read:\n{}\nThe memory card will NOT be saved.\nYou must "
+                                             "delete the memory card manually if you want to save."),
+                  Path::GetFileName(filename), error.GetDescription()),
+      Host::OSD_CRITICAL_ERROR_DURATION);
     mc->Format();
+    mc->m_filename = {};
+    mc->m_changed = false;
   }
 
   return mc;
@@ -352,7 +358,7 @@ bool MemoryCard::SaveIfChanged(bool display_osd_message)
     if (display_osd_message)
     {
       Host::AddIconOSDMessage(std::move(osd_key), ICON_FA_SD_CARD,
-                              fmt::format(TRANSLATE_FS("OSDMessage", "Failed to save memory card to '{}': {}"),
+                              fmt::format(TRANSLATE_FS("MemoryCard", "Failed to save memory card to '{}': {}"),
                                           Path::GetFileName(display_name), error.GetDescription()),
                               Host::OSD_ERROR_DURATION);
     }
@@ -364,7 +370,7 @@ bool MemoryCard::SaveIfChanged(bool display_osd_message)
   {
     Host::AddIconOSDMessage(
       std::move(osd_key), ICON_FA_SD_CARD,
-      fmt::format(TRANSLATE_FS("OSDMessage", "Saved memory card to '{}'."), Path::GetFileName(display_name)),
+      fmt::format(TRANSLATE_FS("MemoryCard", "Saved memory card to '{}'."), Path::GetFileName(display_name)),
       Host::OSD_QUICK_DURATION);
   }