v2/handler: fix typo in assert message
v2/handler: fix typo in assert message

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