The upgrade at some point then trigger to update to the latest TypeScript toolset version (2.1 at the time of writing).
We then notice a series of TypeScript compiler errors with codes TS2300 and TS2374. It turns out that the compiler was actually happy. The error list is created by IntelliSense. To identify them as generated by IntelliSense you need to ensure that you select "IntelliSense Only" from the drop-down list in the "Error List" view of Visual Studio (VS) (click image to enlarge it):
In our case we observed the following errors:
- TS2300 Duplicate identifier 'export='
- TS2374 Duplicate string index signature
- TS2375 Duplicate number index signature