[MISC] Apply second review

Signed-off-by: Lydia Buntrock <[email protected]>

include/sharg/validators.hpp

@@ -602,23 +602,12 @@ class output_file_validator : public file_validator_base
     output_file_validator & operator=(output_file_validator &&) = default;      //!< Defaulted.
     virtual ~output_file_validator() = default; //!< Virtual Destructor.
 
-    /*!\brief Constructs from a given overwrite mode.
-     * \param[in] mode A sharg::output_file_open_options indicating whether the validator throws if a file already
-                       exists.
-     */
-    explicit output_file_validator(output_file_open_options const mode)
-        : file_validator_base{}, mode{mode}
-    {
-        file_validator_base::extensions = std::move(std::vector<std::string> {});
-        file_validator_base::extensions_str = std::string {};
-    }
-
     /*!\brief Constructs from a given overwrite mode and a list of valid extensions.
      * \param[in] mode A sharg::output_file_open_options indicating whether the validator throws if a file already
                        exists.
      * \param[in] extensions The valid extensions to validate for.
      */
-    explicit output_file_validator(output_file_open_options const mode, std::vector<std::string> extensions)
+    explicit output_file_validator(output_file_open_options const mode, std::vector<std::string> extensions = {})
         : file_validator_base{}, mode{mode}
     {
         file_validator_base::extensions = std::move(extensions);