Fix valgrind warning

Author: vdweide

Common/src/CConfig.cpp

@@ -2832,7 +2832,7 @@ void CConfig::SetConfig_Parsing(char case_filename[MAX_STRING_SIZE]) {
      * If there is a statement after a cont. char
      * throw an error. ---*/
 
-     if (text_line.front() != '%'){
+     if (text_line.size() && (text_line.front() != '%')){
        while (text_line.back() == '\\' ||
               (PrintingToolbox::split(text_line, '\\').size() > 1)){
          string tmp;