message: not neccessary that filename is found so it has to be checked
diff: @@ -267,7 +267,10 @@ void DiffView::diffTreeModelDataChanged(const QModelIndex &topLeft,
  loadStagedPatches();
  QString filename = file->name();
  - git::Patch stagedPatch = mStagedDiff.patch(mStagedPatches[file->name()]);
  + git::Patch stagedPatch;
  + const int index = mStagedPatches.value(file->name(), -1);
  + if (index != -1)
  + stagedPatch = mStagedDiff.patch(index);
  file->updateHunks(stagedPatch);
  file->setStageState(stageState);
  