wbdata does not handle indicators with no data

[EdGaere]

Problem: Some indicators have no data but wbdata loops endlessly, incrementing the requested page on each request.

Example
https://api.worldbank.org/v2/sources/85/indicators

Response

<wb:indicators page="1" pages="0" per_page="50" total="0"/>

Solution: early exit if WorldBank API returns pages=0

fetcher.py

def fetch(url, ..):
    while pages != this_page:
        ...
        if pages == 0: # early exit if WorldBank API returns pages=0
            break

[OliverSherouse]

Thanks for the report, I'll get that patched and try not to think about why they have indicators with no data.