After upgrading Octoprint to version 1.10.0 PrettyGCode shows empty window

[anderl1969]

After upgrading Octoprint to 1.10.0 the PGcode-plugin most of the time doesn't work:

• it shows an empty window
• no reaction to the buttons in the top right corner (toggle settings window, toggle fullscreen mode)

Sometimes the plugin works as usual, but most of the time it doesn't.