check ref/unref on _handle in net.socket

Author: kjin

lib/internal/http2/core.js

@@ -1122,19 +1122,13 @@ class Http2Session extends EventEmitter {
 
   ref() {
     if (this[kSocket]) {
-      assert(this[kSocket]._handle);
-      if (typeof this[kSocket]._handle.ref === 'function') {
-        this[kSocket].ref();
-      }
+      this[kSocket].ref();
     }
   }
 
   unref() {
     if (this[kSocket]) {
-      assert(this[kSocket]._handle);
-      if (typeof this[kSocket]._handle.unref === 'function') {
-        this[kSocket].unref();
-      }
+      this[kSocket].unref();
     }
   }
 }

lib/net.js

@@ -1140,7 +1140,9 @@ Socket.prototype.ref = function() {
     return this;
   }
 
-  this._handle.ref();
+  if (typeof this._handle.ref === 'function') {
+    this._handle.ref();
+  }
 
   return this;
 };
@@ -1152,7 +1154,9 @@ Socket.prototype.unref = function() {
     return this;
   }
 
-  this._handle.unref();
+  if (typeof this._handle.unref === 'function') {
+    this._handle.unref();
+  }
 
   return this;
 };