[FEATURE] Add helpful error messages

[oliverklee]

Summary / Description

Currently, my TER release is failing with the following message:
No or invalid ext_emconf.php found in the folder.

I'd like to have specific error messages like this so I know what the problem is:

• file ext_emconf.php missing
• $EM_CONF not set
• $EM_CONF is no array
• version info missing in $EM_CONF
• typo3 dependency missing in $EM_CONF
• version number 1.2.3 in $EM_CONF is different than the version number 1.2.4 provided as an argument

[o-ba]

Hi, this sound reasonable. Do you want to create a PR for it?

[oliverklee]

Yes, will do. (It might take a few days, though.)

[o-ba]

Hi @oliverklee, do you still plan to add a PR for this issue?

[oliverklee]

Yes. I hope that I’ll get it done during the T3DD22 coding night.

[josefglatz]

Any update on this?

[oliverklee]

No, unfortunately not, and I currently don't know yet when I'll have time for this. Sorry.

If anyone would be willing to step in, that would help.