Fix batchCallBuffer timeout handling

rpc/handler.go

@@ -158,7 +158,14 @@ func (b *batchCallBuffer) timeout(ctx context.Context, conn jsonWriter) {
 	for _, msg := range b.calls {
 		if !msg.isNotification() {
 			resp := msg.errorResponse(&internalServerError{errcodeTimeout, errMsgTimeout})
-			b.resp = append(b.resp, resp)
+			serialized, err := json.Marshal(resp)
+			if err != nil {
+				conn.writeJSON(ctx, errorMessage(&parseError{"error serializing timeout error: " + err.Error()}), true)
+				b.wrote = true
+				return
+			}
+
+			b.resp = append(b.resp, serialized)
 		}
 	}
 	b.doWrite(ctx, conn, true)
@@ -243,7 +250,7 @@ func (h *handler) handleBatch(msgs []*jsonrpcMessage) {
 			resp := h.handleCallMsg(cp, msg)
 			err := callBuffer.pushResponse(resp)
 			if err != nil {
-				h.conn.writeJSON(cp.ctx, errorMessage(err))
+				h.conn.writeJSON(cp.ctx, errorMessage(err), true)
 				return
 			}
 		}