Improve error message when "Dmul" is used (or error detection in general? unsure)

[lubianat]

when running a batch for new items, I got a cryptic error on qs-dev
https://qs-dev.toolforge.org/batch/31766/

not sure if it is the syntax or the "Dmul"

in the old QS v2 I get

so syntax is correct for QSv2, but I mistakenly used a "mul" description. But the software was kind enough to let me know what I had gotten wrong

[arcstur]

Thanks @lubianat , I think we can make some code that parses the errors and provides them in a more user-friendly way. Transform "invalid key mul in item/description" into something more understandable. Thanks for the issue :D

[lubianat]

That is good enough I think, but I could not find it I guess? Also: multiple lines for the create, while qs2 shows only one, so maybe there is something else going on