[FIX] fix error message in sendMessageReliably

rxin

Author: Xiangrui Meng <meng@databricks.com>

Closes #2120 from mengxr/sendMessageReliably and squashes the following commits:

b14400c [Xiangrui Meng] fix error message in sendMessageReliably

(cherry picked from commit fd8ace2d9a796f69ce34ad202907008cd6e4d274)
Signed-off-by: Josh Rosen <joshrosen@apache.org>