http2: fix session[kSession] undefined issue

`finishSessionDestroy` session cleanup when already done.
PR-URL: #24547Fixes: #24546
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ouyang Yadong <oyydoibh@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: leeight

lib/internal/http2/core.js

@@ -1996,6 +1996,7 @@ class Http2Stream extends Duplex {
 // attempt to gracefully close the session.
 conststate=this[kState];
 if(this.headersSent&&
+this[kSession]&&
 this[kSession][kType]===NGHTTP2_SESSION_SERVER&&
 !(state.flags&STREAM_FLAGS_HAS_TRAILERS)&&
 !state.didRead&&

test/parallel/test-http2-server-session-destroy.js

@@ -0,0 +1,20 @@
+'use strict';
+
+constcommon=require('../common');
+if(!common.hasCrypto)
+common.skip('missing crypto');
+consth2=require('http2');
+
+constserver=h2.createServer();
+server.listen(0,common.localhostIPv4,common.mustCall(()=>{
+constafterConnect=common.mustCall((session)=>{
+session.request({':method': 'POST'}).end(common.mustCall(()=>{
+session.destroy();
+server.close();
+}));
+});
+
+constport=server.address().port;
+consthost=common.localhostIPv4;
+h2.connect('http://'+host+':'+port,afterConnect);
+}));