all: Fix check for empty string (#8456)

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>

lib/model/folder_sendrecv.go

@@ -737,7 +737,7 @@ func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo, snap *db.Snaps
 		l.Debugf("need symlink\n\t%v\n\t%v", file, curFile)
 	}
 
-	if len(file.SymlinkTarget) == 0 {
+	if file.SymlinkTarget == "" {
 		// Index entry from a Syncthing predating the support for including
 		// the link target in the index entry. We log this as an error.
 		f.newPullError(file.Name, errIncompatibleSymlink)

lib/model/model.go

@@ -511,7 +511,7 @@ func (m *model) cleanupFolderLocked(cfg config.FolderConfiguration) {
 }
 
 func (m *model) restartFolder(from, to config.FolderConfiguration, cacheIgnoredFiles bool) error {
-	if len(to.ID) == 0 {
+	if to.ID == "" {
 		panic("bug: cannot restart empty folder ID")
 	}
 	if to.ID != from.ID {