output: #fixed code
                                  public static String getMusterPfadVlc() {
          final String PFAD_LINUX_VLC = "/usr/bin/vlc";
          final String PFAD_MAC_VLC = "/Applications/VLC.app/Contents/MacOS/VLC";
          final String PFAD_WIN_DEFAULT = "C:\\Programme\\VideoLAN\\VLC\\vlc.exe";
          final String PFAD_WIN = "\\VideoLAN\\VLC\\vlc.exe";
          String pfad;
          switch (getOs()) {
              case OS_LINUX:
                  pfad = PFAD_LINUX_VLC;
                  break;
              case OS_MAC:
                  pfad = PFAD_MAC_VLC;
                  break;
              case OS_WIN_32BIT:
              case OS_WIN_64BIT:
              case OS_UNKNOWN:
              default:
                  if (System.getenv("ProgramFiles") != null) {
                      pfad = System.getenv("ProgramFiles") + PFAD_WIN;
                  } else if (System.getenv("ProgramFiles(x86)") != null) {
                      pfad = System.getenv("ProgramFiles(x86)") + PFAD_WIN;
                  } else {
                      pfad = PFAD_WIN_DEFAULT;
                  }
          }
          if (!new File(pfad).exists()) {
              pfad = "";
          }
          return pfad;
      }
input: #vulnerable code 
                                  public static String getMusterPfadVlc() {
          final String PFAD_LINUX_VLC = "/usr/bin/vlc";
          final String PFAD_MAC_VLC = "/Applications/VLC.app/Contents/MacOS/VLC";
          String pfad = "";
          if (System.getProperty("os.name").toLowerCase().contains("windows")) {
              pfad = getWindowsVlcPath();
          } else if (System.getProperty("os.name").toLowerCase().contains("linux")) {
              pfad = PFAD_LINUX_VLC;
          } else if (System.getProperty("os.name").toLowerCase().contains("mac")) {
              pfad = PFAD_MAC_VLC;
          }
          if (new File(pfad).exists()) {
              return pfad;
          } else {
              return "";
          }
      } 
                              #location 5 
                              #vulnerability type NULL_DEREFERENCE