ams: mark ams::Result [[nodiscard]] (partially complete).

NOTE: This work is not yet fully complete; kernel is done, but
it was taking an exceedingly long time to get through libstratosphere.
Thus, I've temporarily added -Wno-error=unused-result for libstratosphere/stratosphere.

All warnings should be fixed to do the same thing Nintendo does as relevant, but this
is taking a phenomenally long time and is not actually the most important work to do,
so it can be put off for some time to prioritize other tasks for 21.0.0 support.

libraries/libstratosphere/source/erpt/srv/erpt_srv_main.cpp

@@ -56,8 +56,8 @@ namespace ams::erpt::srv {
             fs::DisableAutoSaveDataCreation();
 
             /* Extend the system save data. */
-            /* NOTE: Nintendo does not check result of this. */
-            ExtendSystemSaveData();
+            /* NOTE: Nintendo used to not check the result of this; they do now, but . */
+            static_cast<void>(ExtendSystemSaveData());
 
             R_TRY_CATCH(fs::MountSystemSaveData(ReportStoragePath, SystemSaveDataId)) {
                 R_CATCH(fs::ResultTargetNotFound) {
@@ -97,7 +97,7 @@ namespace ams::erpt::srv {
             }
 
             if (report_count >= MinimumReportCountForCleanup) {
-                fs::CleanDirectoryRecursively(ReportOnSdStorageRootDirectoryPath);
+                static_cast<void>(fs::CleanDirectoryRecursively(ReportOnSdStorageRootDirectoryPath));
             }
         }
 
@@ -110,7 +110,9 @@ namespace ams::erpt::srv {
             AMS_ABORT_UNLESS(ctx != nullptr);
         }
 
-        Journal::Restore();
+        if (R_FAILED(Journal::Restore())) {
+            /* TODO: Nintendo deletes system savedata when this fails. Should we?. */
+        }
 
         Reporter::UpdatePowerOnTime();
         Reporter::UpdateAwakeTime();