Fix panic

entry.go

@@ -286,6 +286,7 @@ func ReadEntry(url string) (entry *Entry, err error) {
 	}
 	fileContent, _, exists, err := SelectedStorage.ReadFile(filePath)
 	if err != nil || !exists {
+		err = errors.New("failed to read file or entry doesn't exist")
 		return
 	}
 	entry, err = ReadHugoPost(fileContent)