NullPointerException in WorthwhileFoldingRegionProvider when opening malformed files

[bafain]

1. Create a new Worthwhile Project in the Project Explorer named "testprogramme"
2. Import validierung/testprogramme/*.ww into the newly created Worthwhile Project

3. Open one of the just imported Worthwhile Files (such as test_division.ww)

   function division(a : Integer, b : Integer) : Integer {
      c : Integer := b
      d : Integer := 0
      if( b ≥ 0) {
          while(c ≤ a) {
                  c := c + b
                  d := d + 1
          }
      }
      return d
   }

4. gist: f75e230c2185796bbadb