Aaron 出错日志如下：
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x454ab8]
goroutine 4786 [running]:
time.stopTimer(0xc00009aaa8, 0x19b3b80)
/usr/local/go/src/runtime/time.go:224 +0x32
time.(Timer).Stop(...)
/usr/local/go/src/time/sleep.go:78
net/http.(http2clientConnReadLoop).cleanup(0xc0022c3fa8)
/usr/local/go/src/net/http/h2_bundle.go:8210 +0x114
net/http.(http2ClientConn).readLoop(0xc0013ccc00)
/usr/local/go/src/net/http/h2_bundle.go:8180 +0x129
created by net/http.(http2Transport).newClientConn
/usr/local/go/src/net/http/h2_bundle.go:7174 +0x651
