Describe the bug
The package @cubejs-client/core defines its dependency on cross-fetch as "cross-fetch": "^3.0.2", however if this is resolved to cross-fetch 3.2.0 an error is thrown by cube-client when making requests to the server:

TypeError: Can only call Window.fetch on instances of Window
  fetch
  (anonymous function) — cubejs-client-core.cjs.js:2190
  s — regeneratorRuntime.js:75
  (anonymous function) — regeneratorRuntime.js:58
  asyncGeneratorStep — asyncToGenerator.js:3
  _next — asyncToGenerator.js:17
  (anonymous function) — asyncToGenerator.js:22
  Promise
  (anonymous function) — asyncToGenerator.js:14
  (anonymous function) — cubejs-client-core.cjs.js:2591

If instead we pin cross-fetch to 3.1.8 the error goes away. It also seems that the error started happening since cube 1.3.16.

Expected behavior
The request is executed without error.

Version:
1.3.23 (started happening on 1.3.16).

Additional context
Might be related to lquixada/cross-fetch#204