current folder in plugin

[Ofnuts]

Yes, in the Gimp standard error stream. But on Windows it is typically hidden (but I think you can get at it if you start Gimp with gimp-console.exe).

Otherwise:

• You can catch the worst blunders (unbalanced parentheses, indentation...) by trying to run the code in a command prompt (it should fail, but not elicit syntax errors)
  
• You bracket the code in a try/except block, and display the Python error in a Gimp message.
  

See examples in most of my scripts....