etcdmain: check error before assigning peer transport

Or it may panic when new transport fails, e.g., TLS info is invalid.

etcdmain/etcd.go

@@ -314,10 +314,10 @@ func startProxy(cfg *config) error {
 	}
 
 	pt, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, time.Duration(cfg.proxyDialTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyReadTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyWriteTimeoutMs)*time.Millisecond)
-	pt.MaxIdleConnsPerHost = proxy.DefaultMaxIdleConnsPerHost
 	if err != nil {
 		return err
 	}
+	pt.MaxIdleConnsPerHost = proxy.DefaultMaxIdleConnsPerHost
 
 	tr, err := transport.NewTimeoutTransport(cfg.peerTLSInfo, time.Duration(cfg.proxyDialTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyReadTimeoutMs)*time.Millisecond, time.Duration(cfg.proxyWriteTimeoutMs)*time.Millisecond)
 	if err != nil {