Fix crash accessing serverSubs from non-syncQueue

[seidju]

• handle access to serversSubs dict only from syncQueue
• minor code-style refactoring

[FZambia]

Thanks for a fix!

Looking at formatting changes - how those were generated? When I am trying to re-format the code using ctrl + i in XCode I get the different format style. Not sure I really want all these changes to be merged at this point since there is an ongoing work on next SDK iteration in https://github.com/centrifugal/centrifuge-swift/tree/new_protocol branch

[seidju]

@FZambia It was made by AppCode, I can re-submit PR without changes of code-style, I guess it would be better

[FZambia]

I can re-submit PR without changes of code-style, I guess it would be better

Yep, thanks, will definitely simplify the workflow at this point