Bugfix - Regression: First run of Oni doesn't open a window

[bryphe]

This is a regression of #2377 - the manifestation is that, when first launching Oni, nothing happens - it takes a second launch to actually see the window.

The issue is that, we call makeSingleInstance, and the callback for that gets fired when any additional instance is opened, however, we weren't handling the initial case - if isSecondInstance is false, than we need to kick off the window launch explicitly after the 'ready' event is fired.

Thanks @CrossR for catching this! 💯

[CrossR]

Fixed it for me!

[codecov]

Codecov Report

Merging #2380 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #2380   +/-   ##
======================================
  Coverage    38.1%   38.1%           
======================================
  Files         300     300           
  Lines       12522   12522           
  Branches     1646    1646           
======================================
  Hits         4771    4771           
  Misses       7497    7497           
  Partials      254     254

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8919a86...a213879. Read the comment docs.