feat(conversations): align toggle priority fallback

internal/handler/api/v1/conversation_handler.go

@@ -576,9 +576,11 @@ func (h *ConversationHandler) TogglePriority(c *gin.Context) {
 	var req struct {
 		Priority *string `json:"priority"`
 	}
-	if err := c.ShouldBindJSON(&req); err != nil {
-		response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
-		return
+	if c.Request.Body != nil && c.Request.Body != http.NoBody {
+		if err := c.ShouldBindJSON(&req); err != nil && !errors.Is(err, io.EOF) {
+			response.AbortWithStatusError(c, http.StatusBadRequest, response.ErrValidation, err.Error())
+			return
+		}
 	}
 	priority := ""
 	if req.Priority != nil {