Fixed this error in the next release. This error occurs if you attempt to analyze Area Permissions when choosing the wiki index or omitting the area you want to analyze.
I should note that Analyze Permissions does not show file-type or widget permissions, so it will probably not be helpful for you right now. We should probably add that to the results. However, since attachments can't even be uploaded inside the index (they must be inside an area), this analyze result probably wouldn't be too helpful either.