[Backport v6.x] fix: Fixed the issue that there is no running request when http2 goaway (#3877)

Co-authored-by: 沈鸿飞 <[email protected]>

Author: github-actions[bot]

lib/dispatcher/client-h2.js

@@ -242,11 +242,12 @@ function onHTTP2GoAway (code) {
   util.destroy(this[kSocket], err)
 
   // Fail head of pipeline.
-  const request = client[kQueue][client[kRunningIdx]]
-  client[kQueue][client[kRunningIdx]++] = null
-  util.errorRequest(client, request, err)
-
-  client[kPendingIdx] = client[kRunningIdx]
+  if (client[kRunningIdx] < client[kQueue].length) {
+    const request = client[kQueue][client[kRunningIdx]]
+    client[kQueue][client[kRunningIdx]++] = null
+    util.errorRequest(client, request, err)
+    client[kPendingIdx] = client[kRunningIdx]
+  }
 
   assert(client[kRunning] === 0)