Use the "fork-ts-checker-webpack-plugin" for parallel type checks

[lslezak]

Problem

• The TypeScript type checks are disabled in development builds, they run only in the production build
• The reason is probably the slowdown caused by the checks
  • Development build with type checks off (the default): ~10 seconds
  • Development build with type checks on (explicitly enabled in the config): ~15 seconds
  • So enabling the type checks increases the build time +50% 😟

Solution

• Use the fork-ts-checker-webpack-plugin which runs the type checks in parallel in a separate process so the main webpack build is not affected and runs with the disabled checks.

Testing

• Tested manually
• With the type checks enabled the development build takes about 10 seconds, the same time as originally with type checks off. 👍 So there should be no slowdown even with enabled checks.
• It helps to speed up the production builds as well:
  • Original production build: ~20 seconds
  • Production build with parallel type checks: ~15 seconds
  • So the production build is about 25% faster! 😃

[coveralls]

coverage: 64.147%. remained the same
when pulling f95a2d0 on fork-ts-checker-webpack-plugin
into 6286f70 on master.