Bug/4727 crashing form after changing user variable to array

[robinmolen]

Closes #4727

Changes

Fixes the crashes on user variable dataType change, when a initialValue is defined. This crash happend when changing any dataType to the array dataType, because the component for the array dataType used the .some js array function. (It expected that the value was an array, so this function was used without any checks)

To resolve this situation, and possible similar situations in the future, the initialValue now gets transformed when the dataType changes. This transformation could result into losing the previous initialValue. To make sure that the dataType change is intentional, a confirmation message will be shown.

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • [x] Checked copying a form
  • [x] Checked import/export of a form
  • [x] Config checks in the configuration overview admin page
  • [x] Problem detection in the admin email digest is handled

• Release management

  • [x] I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • [x] Ran ./bin/makemessages_js.sh
  • [x] Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • [x] Commit messages refer to the relevant Github issue
  • [x] Commit messages explain the "why" of change, not the how

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.55%. Comparing base (7a6e0d3) to head (1352126). Report is 6 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4797 +/- ## ======================================= Coverage 96.55% 96.55% ======================================= Files 748 748 Lines 25413 25413 Branches 3358 3358 ======================================= Hits 24538 24538 Misses 610 610 Partials 265 265 ```

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[sergei-maertens]

Backports:

• 2.8.x: 3f955b622184719155a92d6e340e2013e3368e67
• 2.7.x: 43272cd17e4966106a1102602b969def44114849