Merge pull request #26 from niklas88/fix_crash

Thanks for this fix, you're obviously right. I guess it's a refactoring error that happened when I created the method from what has initially just chained for the only two permutations at that time: pso and pos

src/index/Index.cpp

@@ -857,7 +857,7 @@ void Index::scanNonFunctionalRelation(const pair<off_t, size_t>& blockOff,
       } else {
         LOG(TRACE) << "Special case: extra scan of follow block!\n";
         pair<Id, off_t> follower;
-        _psoFile.read(&follower, sizeof(follower), followBlock.first);
+        indexFile.read(&follower, sizeof(follower), followBlock.first);
         nofBytes = static_cast<size_t>(follower.second - it->second);
       }
     }
@@ -1135,4 +1135,4 @@ void Index::setKbName(const string& name) {
   _sopMeta.setName(name);
   _ospMeta.setName(name);
   _opsMeta.setName(name);
-}
+}