How to investigate Python script error

Hi

Thanks for your help and inputs.. I have no choice at the end, but go thru my data segment and segments and see which part of the data that may be causing the issue.

So the problem at the end is that is that a few of the "PortfolioName" (x in the loop) in aList does not match the dataset table "PortfolioName", hence producing some empty dataframe which hence cannot be merged in PowerBI. This name mismatch problem did not cause a problem in Python based application however, it must somehow ignore the empty dataframe, and continue the loop. 

Anyway, woud be nice to have a way to debug Python codes in PowerBI.. as it seems to behave slightly differently in PowerBI, and find it hard how to identify the issue - if is a data issue, how powerbi execute the python codes or something else....

Many thanks

Jonathan