Show Degree Distribution or Betweenness assume current network has been analyzed

If Degree or Betweenness don't exist, half-built window appears

STR: open pathway, click buttons in Analyzer's results panel

Start by opening a pathway and reproducing the issue from the Analyzer's results panel, then inspect the Degree and Betweenness actions and the window they open when their results are absent. Done means those buttons no longer produce a half-built window when the current network has not been analyzed.

Written by the indexing model from the issue text.