I tried several solutions that worked fine.
You passed the kata and your solution got warnings:

solution.swift:6:5: warning: initialization of variable 'key' was never used; consider replacing with assignment to '_' or removing it
var key=0;
~~~~^~~
_
solution.swift:7:7: warning: initialization of variable 'locSpace' was never used; consider replacing with assignment to '_' or removing it
  var locSpace=0
  ~~~~^~~~~~~~
  _

It's not a kata issue but if you think the compiler is at fault you can report a bug at:https://github.com/Codewars/codewars.com/issues.

Now, this is interesting. Can you share your code so the issue could be investigated and reported as the potential runner bug?
Also, there's no Swift 5.2 available for me?