Fix sync-i18n script throwing a compile error & added some missing translation keys

[alexandrevryghem]

References

• Fixes item types in dso-selector component are not getting translated #598

Description

Currently the sync-i18n script can't be executed because of a type issue caused by the Typescript 4.4 update. Because this PR was ridiculously small I also fixed another issue at the same time. The second fix makes the DSO type in the dso-selector translatable.

Instructions for Reviewers

List of changes in this PR:

• Added an if statement to sync-i18n-files.ts to verify that the variable returned by the catch block is of type Error
• Added translation keys for the 3 DSO types that use the dso-selector: Community, Collection & Item

Guidance for how to test/review this PR:

• Verify that you can run the sync-i18n script again
• Verify that the DSO selector now show the translated community/collection/item in French/Dutch
• Verify that it also works when a DSo selector contains multiple different types of DSO types (for example the scope selector on the search page)

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using yarn lint
• My PR doesn't introduce circular dependencies (verified via yarn check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[tdonohue]

👍 Thanks @alexandrevryghem ! Tested this locally and could reproduce the bug. This fixes it. The missing i18n keys look correct too