lit.dev typescript error 'TemplateResult' is not generic

Question

I am using [email protected]

When building my typescript component it adds this as the my-component.d.ts:

render(): import("lit-html").TemplateResult<1> | undefined;

Problem is that this throws an error:

 error TS2315: Type 'TemplateResult' is not generic.

I am using [email protected]

Can anyone tell me why this is happening ?