Incorrect or no canonical tag on categorie and detail pages

[DanielleCuppen]

Describe the bug
Underlying pages in the categories ( and tags) show an incorrect or no
canonical tag, this causes several problems with indexing in Google Search console.

To Reproduce

1. Go to 'https://www.fronteers.nl'
2. Click on 'https://www.fronteers.nl/nl/activiteiten/'
3. Scroll down to 'Bijeenkomst bij Capgemini'
4. Click on 'View details'
5. view source, there's no canonical

------or/and

6. Go to 'https://www.fronteers.nl/nl/blog/'
7. Click on 'categorie > browsers'
8. Click on '25% Fronteers-korting op nieuwe browser Polypane' or any other detail page
9. Click on 'View details'
10. view source, theres a wrong canonical (nieuwe website)

Expected behavior
Write/show the correct canonical tags.

Screenshots

[SleeplessByte]

I am attempting to resolve this (draft: #414, doesn't work yet)