fix RequestCtx is canceled (#1879)

Create done channel in fakeServer during the initialization of newRequestCtx to prevent the done channel from being nil

server.go

@@ -2789,6 +2789,7 @@ func (ctx *RequestCtx) Value(key any) any {
 }
 
 var fakeServer = &Server{
+	done: make(chan struct{}),
 	// Initialize concurrencyCh for TimeoutHandler
 	concurrencyCh: make(chan struct{}, DefaultConcurrency),
 }

server_test.go

@@ -4414,3 +4414,13 @@ func TestRequestBodyStreamReadIssue1816(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestRequestCtxInitShouldNotBeCanceledIssue1879(t *testing.T) {
+	var r Request
+	var requestCtx RequestCtx
+	requestCtx.Init(&r, nil, nil)
+	err := requestCtx.Err()
+	if err != nil {
+		t.Fatal(err)
+	}
+}