Invalid API version

 info   Building visual...
 error  UNKNOWN TypeError: Path must be a string. Received undefined
    at assertPath (path.js:28:11)
    at VisualPackage.join (path.js:503:7)
    at VisualPackage.buildPath (C:\Users\degeestl\AppData\Roaming\npm\node_modules\powerbi-visuals-tools\lib\VisualPackage.js:115:26)
    at Promise (C:\Users\degeestl\AppData\Roaming\npm\node_modules\powerbi-visuals-tools\lib\LessCompiler.js:53:42)
    at new Promise (<anonymous>)
    at Function.build (C:\Users\degeestl\AppData\Roaming\npm\node_modules\powerbi-visuals-tools\lib\LessCompiler.js:52:16)
    at _validateApiVersion.then (C:\Users\degeestl\AppData\Roaming\npm\node_modules\powerbi-visuals-tools\lib\VisualBuilder.js:100:38)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:188:7)
    at Function.Module.runMain (module.js:667:11)

When first running the project, we get an error:

λ pbiviz start
 info   Building visual...
 error  VALIDATION   Invalid API Version v2.1.0

After doing a pbiviz update 2.1.0:

λ pbiviz update 2.1.0
 info   Visual api 2.1.0 updated

After running again:

λ pbiviz start
 info   Building visual...
 error  VALIDATION   The PowerBI-visuals.d.ts in your tsconfig.json must match the api version in pbiviz.json (expected: .api/v2.1.0/PowerBI-visuals.d.ts)

Then we update the tsconfig.json files as follows:

  "files": [
    ".api/v2.1.0/PowerBI-visuals.d.ts",
    "./src/visual.ts"
  ]

Finally we get the above mentioned error. This seems to be generated when building the package.