lib: fix zlib async callback after close

Closing a zlib stream may throw an uncaught exception afterwards if
there was a pending callback still to be invoked. This adds a very
minimal fix to the issue as all of this code has been rewritten in later
versions.

Fixes: #15625
PR-URL: #16312
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>

Author: nakedible

lib/zlib.js

@@ -595,7 +595,7 @@ Zlib.prototype._processChunk = function(chunk, flushFlag, cb) {
       this.callback = null;
     }
 
-    if (self._hadError)
+    if (self._hadError || !self._handle)
       return;
 
     var have = availOutBefore - availOutAfter;