fix(core/select): check if value is defined, before updating selection

[matthiashader]

Addition to #1548

💡 What is the current behavior?

• select in angular logs an error to the console when initializing the select-items in async
• last element has always an undefined value
• angular seems to initialize components differently than react (possibly due to the vdom)

GitHub Issue Number: N/A, [IX-1918]

🆕 What is the new behavior?

• before the selection is updated, it is checked if the value is defined
• valueChange emited and selection updated
• updateSelection still needed when select properties change!
• removed "get dropdownItem()", method is never called - only appearance in select.tsx does not call this methods
• only needed for the addItem, which is not a select-item (it is a dropdown-item)
• label / value changes only occur after the components has been initalised -> fewer events are thrown, also the slotChange takes care about added / deleted slots

🏁 Checklist

A pull request can only be merged if all of these conditions are met (where applicable):

• 🦮 Accessibility (a11y) features were implemented
• 🗺️ Internationalization (i18n) - no hard coded strings
• 📲 Responsiveness - components handle viewport changes and content overflow gracefully
• 📄 Documentation was reviewed/updated (pnpm run docs)
• 🧪 Unit tests were added/updated and pass (pnpm test)
• 📸 Visual regression tests were added/updated and pass (Guide)
• 🧐 Static code analysis passes (pnpm lint)
• 🏗️ Successful compilation (pnpm build, changes pushed)

👨‍💻 Help & support

[changeset-bot]

🦋 Changeset detected

Latest commit: 27c39bc

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@siemens/ix	Patch
@siemens/ix-angular	Patch
@siemens/ix-react	Patch
@siemens/ix-vue	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

Report of strict check

src/components/select/select.tsx

• src/components/select/select.tsx(336,5): error TS2322: Type '(string | undefined)[]' is not assignable to type 'string[]'.: error TS2322: Type '(string | undefined)[]' is not assignable to type 'string[]'.
• src/components/select/select.tsx(437,24): error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.: error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
• src/components/select/select.tsx(575,12): error TS18048: 'item.label' is possibly 'undefined'.: error TS18048: 'item.label' is possibly 'undefined'.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud