ODI 12c - Buffer too small for CLOB to CHAR or BLOB to RAW conversion

We have an error message refresh variable in which it is trying to get the error message from snp_session table (schema : OD_BI_REPO) where it is converting the clob message to char as varchar2(3000) getting below error:

Caused by: java.sql.SQLException: ORA-22835 : Buffer too small for CLOB to CHAR or BLOB to RAW conversion (actual: 54150, maximum: 32767)

Sql query causing the error:

Select cast(error_message as varchar2(3000)) from (select error_message from snp_session where sess_status ='E' order by sess_beg desc) where rownum <2

Modified query:

Select substr(error_message,1,4000) from (select error_message from snp_session where sess_status ='E' order by sess_beg desc) where rownum <2