> If polling a url n times and breaking if response is 'completed', is the best to approach to use try catch and error() to get around immutability?  I need the full response on complete so I redo the last http get. It is not a biggie requesting twice. Adam

The hof:until function may help you [1]. Don’t hesitate to supply us
with a minimized code snippet.

In general, it’s almost always a good advice not to use try/catch
unless you need to catch real errors.

[1] https://docs.basex.org/wiki/Higher-Order_Functions_Module#hof:until