Improve error tracing in Ruby functions

[samnung]

Given this example of files:

abc.bade

- def raise_some_error1
-   raise_some_error2
- end
-
- def raise_some_error2
-   raise_some_error3
- end
-
- def raise_some_error3
-   raise StandardError
- end

root.bade

import 'abc.bade'
= raise_some_error1

it will produce error with this backtrace:

template backtrace:
  root.bade:25:in `raise_some_error3'
  root.bade:18:in `raise_some_error2'
  root.bade:11:in `raise_some_error1'
  root.bade:10:in `<top>'

Which is wrong.