Class extends value undefined is not a constructor or null

Issue :

When I run my project using node ts-node/register I don’t get any errors, however with ts-jest I receive the following:

 ● Test suite failed to run

    TypeError: Class extends value undefined is not a constructor or null

      at Object.<anonymous> (../node_modules/google-gax/src/grpc.ts:110:43)
      at Object.<anonymous> (../node_modules/google-gax/src/index.ts:32:1)

The file grpc.ts doesn’t actually exist, it’s a JS file really. I wonder why it’s trying to include grpc.ts when only a js file exists.

Expected behavior :

ts-jest should be able to run file like ts-node without the above error.