SemanticDiff fails to generate colors for certain themes and therefore doesn't load

[mmueller2012]

SemanticDiff fails to generate a color palette for certain themes. This leads to an exception during the initialization of the webview and renders SemanticDiff unusable. The problem can be identified by the following exception in the developer console:

Uncaught TypeError: Cannot read properties of undefined (reading '0')
    at a2 (script.js:16:94457)
    at Tu.updateColorTheme (script.js:16:98744)
    at new Tu (script.js:16:96840)
    at script.js:16:118631
    at script.js:16:119322

One theme known to trigger this problem is Cobalt Next.