UI: Fix crash if missing module in context bar

If a module is not found in context bar, it crashed when resolving
source type name. This is same change as 41367bb2b but fixes
window-capture and display-capture.
Also removes an unnecessary pair of braces.
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f