kendo.promptbox.min.js and kendo.chat.min.js each include their own private copy of Kendo's widget registry. That private copy never sets up the ui namespace. When the file tries to register its widget, the registry throws Unknown widget namespace: ui
Go to this Progress Kendo UI Dojo and run it.
The following error appears for the Kendo UI Chat and PromptBox:
Uncaught Error: Unknown widget namespace: ui
The components should be working as expected like when using kendo.all.min.js. (Dojo Example)