no error msg when putrow failed

https://github.com/4paradigm/OpenMLDB/blob/8f19aebb85e1673e7897b7c12d26943ff15c6811/src/sdk/sql_cluster_router.cc#L1274-L1277

ret message is ignored.

The issue points to a specific location in src/sdk/sql_cluster_router.cc where a return message is ignored after a putrow failure. First, examine the surrounding code to understand the error handling pattern. Then, determine how to properly propagate or log the error message. Finally, verify the fix by building and testing the SDK component.

索引モデルが issue の本文から書いたものです。