Add error dialog "Problem finding files"

[IfIWantedTo]

I added an Error Dialog in AutoSetFileLinks. #5890
I decided to open a pull request in order to get feedback on what I've done.

This is my first contribution to OpenSource ever, so beware of stupid mistakes.

I am currently trying to go through the motions of contributing. However, I have run into a
few issues:

 `ERROR org.jabref.logic.l10n.Localization - Messages are not initialized before accessing key: Your current Java version (%0) is not supported. Please install version %1 or higher. - `

• Change in CHANGELOG.md described (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

[Siedlerchr]

@IfIWantedTo Welcome to JabRef!
I will try to give you some context.
Regarding the localization error, this seems your IDE configuration is not correct. Please check with the guide here
https://devdocs.jabref.org/getting-into-the-code/guidelines-for-setting-up-a-local-workspace#configure-your-ide

Back to the code, it's a bit more complicated then simply adding a dialog there.
The method has a loop so therefore a dialog would be a not a good idea for all files

I would propose to create a list with the exceptions in that class
Then in the AutoLinkFilesAction in the succeed method of the linksFilesTask you can check for that list if it has any exceptions and report a notifications (the notify method shows a toast message that there were errors and say sth like go to the log for more details)

[IfIWantedTo]

@Siedlerchr Thank u for your help!

I have completely missed the loop before, thank you! I have replaced the code before with an iteration of
pushing to a list of exceptions as you suggested. I will still have to figure out where exactly to put the calling of notify() but I'm sure I will figure that out once I'm actually able to run the code.

Regarding the IDE: I figured there was a problem with the configuration and I went over the guide multiple times.
When it didn't seem to help I disregarded it. Now that you have confirmed my former suspicions I will resume my efforts.

Again, thank you for your comment! Without you, this would have taken much longer :)

[Siedlerchr]

I would propose to move this into the succeeded methoid here :

jabref/src/main/java/org/jabref/gui/externalfiles/AutoLinkFilesAction.java

Lines 60 to 68 in 5ab494e

	Task<List<BibEntry>> linkFilesTask = new Task<>() {
	@Override
	protected List<BibEntry> call() {
	return util.linkAssociatedFiles(entries, nc);
	}
	@Override
	protected void succeeded() {

[IfIWantedTo]

Oh ok, thank you. Can I ask you a few questions about the succeeded() method?

As far as I understood, it notifies the user when it has set the file links, i.e. when the returned List of linkAssociatedFiles(...) is not empty. In the other case Finished automatically setting external links. No files found. I haven't quite understood yet, how this else case is different from what I am trying to accomplish.

[Siedlerchr]

Sorry for the delay in answering. The succeeded method is called whenever the task is finished normally and doesn't get interrupted.
It either says files found or no files found, but it doesn't tell the user if there was an error (exception) which prevented finding the files.
So one addtional else case (your changes) is to notify the users that there have been X exceptions with the hint
e.g. There were x files with an exception. See log for details

[calixtus]

I tried to finish this PR. Just did not had a file at hand to test the actual auto link, but every other case. So i think this should work, since I did not change the actual logic of the method. So ready for review.

[tobiasdiez]

Thanks @IfIWantedTo for your contribution and @calixtus for finishing this PR.