all: Add failure reporting (fixes #7028) (#6925)

lib/model/folder.go

@@ -865,11 +865,13 @@ func (f *folder) monitorWatch(ctx context.Context) {
 			f.setWatchError(err, next)
 			// This error was previously a panic and should never occur, so generate
 			// a warning, but don't do it repetitively.
-			if !warnedOutside {
-				if _, ok := err.(*fs.ErrWatchEventOutsideRoot); ok {
+			var errOutside *fs.ErrWatchEventOutsideRoot
+			if errors.As(err, &errOutside) {
+				if !warnedOutside {
 					l.Warnln(err)
 					warnedOutside = true
 				}
+				f.evLogger.Log(events.Failure, "watching for changes encountered an event outside of the filesystem root")
 			}
 			aggrCancel()
 			errChan = nil

lib/model/folder_sendonly.go

@@ -65,6 +65,7 @@ func (f *sendOnlyFolder) pull() bool {
 		if !ok {
 			if intf.IsDeleted() {
 				l.Debugln("Should never get a deleted file as needed when we don't have it")
+				f.evLogger.Log(events.Failure, "got deleted file that doesn't exist locally as needed when pulling on send-only")
 			}
 			return true
 		}

lib/model/model.go

@@ -1973,6 +1973,7 @@ func (s *indexSender) sendIndexTo(ctx context.Context) error {
 					l.Warnln("Failed repairing sequence entries:", dbErr)
 					panic("Failed repairing sequence entries")
 				} else {
+					s.evLogger.Log(events.Failure, "detected and repaired non-increasing sequence")
 					l.Infof("Repaired %v sequence entries in database", fixed)
 				}
 			}()