wsutil: Added graceful close checking

Author: diamondburned

utils/wsutil/conn.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"io"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/gorilla/websocket"
@@ -167,6 +168,12 @@ func startReadLoop(conn *websocket.Conn, eventCh chan<- Event) {
 				return
 			}
 
+			// Is the error an intentional close call? Go 1.16 exposes
+			// ErrClosing, but we have to do this for now.
+			if strings.HasSuffix(err.Error(), "use of closed network connection") {
+				return
+			}
+
 			// Check if the error is a normal one:
 			if websocket.IsCloseError(err, websocket.CloseNormalClosure) {
 				return