test/double-response: simplify error assertions
test/double-response: simplify error assertions

RyanTech/tchannel,i/tchannel,hustxiaoc/tchannel,chenwenbin928/tchannel,savaki/tchannel,chenwenbin928/tchannel,hustxiaoc/tchannel,i/tchannel,bunnyblue/tchannel,bunnyblue/tchannel,chenwenbin928/tchannel,sasa233/tchannel,vanloswang/tchannel,vanloswang/tchannel,hustxiaoc/tchannel,Zirpon/tchannel,RyanTech/tchannel,savaki/tchannel,sasa233/tchannel,i/tchannel,sasa233/tchannel,savaki/tchannel,vanloswang/tchannel,bunnyblue/tchannel,Zirpon/tchannel,RyanTech/tchannel,Zirpon/tchannel