Fix graph crash on reload, even out depth sizes

README.md

@@ -306,7 +306,8 @@ links, scroll to zoom. One mouse button pans and the other opens the dot
 you click: right-drag pans and left-click opens by default, or the other way
 round in Settings > Graph. That's also where directories can be hidden
 (leaving only files and the links between them), all made purple instead
-of coloured by depth, or made smaller the deeper they are.
+of coloured by depth, or made smaller the deeper they are (down to a
+file dot's size at depth 5, the red ones).
 
 Rename takes a `/` to move, like the web view (`../Archive/Notes.md`).
 Shortcuts: Enter opens, Backspace goes up, F2 renames, Delete deletes,