Code
T1006 helper-exported
A backend file exports something that is no definition: a function, a value, a class, or a default. A backend file exports only definitions, since a screen file that imports it is handed a record of each definition and nothing else of the file.
Details
A type is no export of this kind: export type and export interface are gone when the file runs.
The fix
Take export away where only this file uses the helper. A helper that other files use lives in a file of its own, which imports neither tentjs nor tentjs/ui.