Fix error while exiting Nightwatch using Ctrl+C.

[garg3133]

Right now, if we try to exit Nightwatch by pressing Ctrl+C, we get an uncaughtException error. This happens because starting with Node 16, a signal of string type (i.e. SIGINT) is emitted on pressing Ctrl+C instead of number type, but process.exit() still accepts a code of number type as the first argument.

This PR fixes this by always exiting the process with code 0 in case a SIGINT signal is encountered. (In Node 14 also, the process used to exit with code 0 upon pressing Ctrl+C.)

[github-actions]

Status

• ❌ No modified files found in the types directory.
  Please make sure to include types for any changes you have made. Thank you!.