TLS: check we're not disconnected before Cleartext blow

lib/tls.js

@@ -233,6 +233,7 @@ CleartextStream.prototype._sucker = function(b) {
 
 CleartextStream.prototype._blower = function(pool, offset, length) {
   debug('reading from clearOut');
+  if (!this.pair._ssl) return -1;
   return this.pair._ssl.clearOut(pool, offset, length);
 };