I agree it makes no sense. I repeated exactly what you describe in a new playground (in Pharo 6.1 on Windows 10) and all worked as expected ��� essentially the same result as Torsten reported in his first post. I wonder if it might be something Mac related in the operation of Playground.
As a desperate try to explain it, please see what happens if you open a Playground with just your single line
and then select ���do it and go���. You should find an inspector pane opening to the right in the Playground, with the result of the parse. If this fails, the standard suggestion is to open a debugger on you error message and try to work back through the stack to see how execution got there.
Just to discourage you further, when you do get to read the contents of the URL, you will find that the USDA have changed everything. All the data are now on a separate web site, probably in a new layout. This is one of the perpetual hassles of web scraping ��� the web site authors have to justify their existence by rewriting everything. I wrote this section of the scraping booklet, working up something I had done as a one-off a year or so earlier, and then I found that the USDA had changed the layout in the interim and much needed to be rewritten.
HTH ��� in part at least.
Peter Kenny
To Torsten ��� I agree I was slipshod in my drafting ��� I was in a hurry. Instead of saying ���can screw things up��� I should have said ���can produce counter-intuitive results���, as exemplified by the fact that, in your first example, ���ingredientsXML��� can mean different things depending on whether you execute it all in one go or a line at a time.
I deleted the playground and entered the text thusly
���do it��� has no complaints
has errors: #new sent to nil
This makes no sense at all.