Fix connection corruption from double-LastHttpContent in streaming pipeline

Server: Guard sendLastHttpContent with state check so it is skipped when
writeError() in makeChunk() already terminated the response. Without this,
a serialization error mid-stream sends two LastHttpContent messages,
corrupting HTTP framing on keep-alive connections.

Client: Null out queueInputStream after signalEndOfStream on LastHttpContent
so spurious content between responses is dropped rather than offered to the
closed stream.

gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/HttpStreamingResponseHandler.java

diff --git a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/HttpStreamingResponseHandler.java b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/HttpStreamingResponseHandler.java
index 6177887..3db50fd 100644
--- a/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/HttpStreamingResponseHandler.java
+++ b/gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/handler/HttpStreamingResponseHandler.java
@@ -150,6 +150,9 @@
                 if (isGraphBinaryResponse()) {
                     if (queueInputStream != null) {
                         queueInputStream.signalEndOfStream();
+                        // Null out so any spurious content arriving between responses is dropped
+                        // rather than offered to the already-closed stream.
+                        queueInputStream = null;
                     }
                     // Reader thread handles completion directly via markComplete/markError
                 } else {

gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java

diff --git a/gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java b/gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java
index fa34d4d..e113aaf 100644
--- a/gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java
+++ b/gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java
@@ -242,7 +242,11 @@
                 // failures that follow this will show up in the response body instead.
                 sendHttpResponse(ctx, OK, createResponseHeaders(ctx, serializer, requestCtx).toArray(CharSequence[]::new));
                 sendHttpContents(ctx, requestCtx);
-                sendLastHttpContent(ctx, HttpResponseStatus.OK, "");
+                // Skip if writeError() already terminated the response (e.g., serialization error in makeChunk).
+                // Sending a second LastHttpContent would corrupt the HTTP framing on keep-alive connections.
+                if (requestCtx.getRequestState() != RequestState.ERROR) {
+                    sendLastHttpContent(ctx, HttpResponseStatus.OK, "");
+                }
             } catch (Throwable t) {
                 writeError(requestCtx, formErrorResponseMessage(t, requestMessage), serializer.getValue1());
             } finally {