[BUG]: specific error details when uploading article files are missing

[humanwebdevelopment]

Describe the bug
The new article unit system is very sensitive to any kind of typo, or unit specific format, however the only error that is reproduced is "A problem has occured: undefined method `[]' for nil:NilClass"

This makes troubleshooting of where this error comes from very complicated, sometimes taking me hours to track the problem. Please include at least an article name or row number as reference to where the error comes from.

#1300 can be one of these causes. But also something small like a capital letter that is missing for the article availability indicator.

Also when the "Delete unavailable articles." is checked during upload, any errors appearing in articles that are not available, will still cause the generic import error. As I am using automatically populated article lists, sometimes articles (and the prices, etc.) are unavailable for a week. Instead of having to delete the product and enter it to the list again the next time it is available, I now add dummy values for price, etc. to avoid the import error for unavailable articles.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
Article / issue specific error logging for uploading articles.

Ignoring errors for unavailable articles

Screenshots
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Foodsoft Version
4.9.1

Logfile
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Additional context
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[lentschi]

@humanwebdevelopment

Thank you for raising this.
Before analyzing this error though: Are you using the current master in production? (That is absolutely not recommended!)

(These snippets were what made it sound to me like you do:)

[...] As I am using automatically populated article lists, sometimes articles (and the prices, etc.) are unavailable for a week.
[...]
Foodsoft Version
4.9.1

Just in case this is unclear:
Production-ready releases can be found here: https://github.com/foodcoops/foodsoft/tags (those not suffixed by '-rc*' obviously)
The current master branch has not yet been released (It will be released as 5.0.0 at some point - hopefully soon - but the version number hasn't yet been incremented.)

[lentschi]

Thank you for raising this.
Before analyzing this error though: Are you using the current master in production? (That is absolutely not recommended!)

This has been clarified elsewhere: Yes, he is using the master.