When the SPFx scaffolded .ts WebPart file is created, an error can be found immediately in the code line protected get dataVersion(): Version {:

The error description is:

"'dataVersion' is defined as a property in class 'BaseClientSideWebPart{I[Name]WebPartProps}', but is overridden here in '[Name]WebPart' as an accessor."

Although the error is not serious and the WebPart compiles and works without any problem, it is extremely annoying. And it is also very simple to solve the problem: add a code line at the top of the 'dataVersion' line indicating:

// @ts-ignore

The error will be gone...