end-of-stream: Test fails with node >= 10.16

Hi,

I had to modify test to pass with node >= 10.16 :

--- a/test.js
+++ b/test.js
@@ -9,7 +9,7 @@
 var ws = fs.createWriteStream('/dev/null');
 eos(ws, function(err) {
        expected--;
-       assert(!!err);
+       assert(!err);
        assert(this === ws);
        if (!expected) process.exit(0);
 });