[fix] Check if client isn't closing/writable
[fix] Check if client isn't closing/writable

In some cases (two plugins with same interval of writes failing to write
at the same time) we'd try to close an already closing client and then
write to a broken pipe. Don't do that.

opsmezzo/forza,npm/forza,mmalecki/forza,mmalecki/forza,mmalecki/forza,opsmezzo/forza,opsmezzo/forza,cloudninja-io/libinterposed