Interpreter: cache getBshPrompt and ensure streams not null.
Interpreter: cache getBshPrompt and ensure streams not null.

Cache the default prompt string retrieved via eval("getBshPrompt();"); for interactive mode, to avoid having to evaluate the string on every command.
Console ensures out and err streams are never null by returning default streams from System if not set.

beanshell/beanshell,beanshell/beanshell,beanshell/beanshell