Can't got the problem,that reproduced on my environment.
Result of running PL/SQL procedure on my PC on Eclipse SQL Explorer:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
If this procedure compiled on other PC on Eclipse SQL Explorer also,that all is OK.
note: If you ask,why Eclipse SQl Explorer - its' historical issue,because procedure isn't compiled under Oracle Sql Developer.
What is problem in my environment?
Thank you.