[Webcomponents]: Fix error message typo

[cmoinier]

Description

This PR fixes a small typo that made error messages not displayed.

Architectural changes

none

Screenshots

none

Quality Assurance Checklist

• Commit history is devoid of any merge commits and readable to facilitate reviews
• If new logic ⚙️ is introduced: unit tests were added
• If new user stories 🤏 are introduced: E2E tests were added
• If new UI components 🕹️ are introduced: corresponding stories in Storybook were created
• If breaking changes 🪚 are introduced: add the breaking change label
• If bugs 🐞 are fixed: add the backport <release branch> label
• The documentation website 📚 has received the love it deserves

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[github-actions]

Affected libs: api-repository, feature-catalog, feature-record, feature-router, feature-search, feature-map, feature-editor, feature-auth, ui-elements, feature-notifications, ui-catalog, ui-search, ui-inputs, feature-dataviz, ui-layout, ui-map, database-dump, api-metadata-converter, data-access-datafeeder, util-data-fetcher, common-fixtures, util-shared, ui-widgets, util-app-config, data-access-gn4, common-domain, ui-dataviz, util-i18n,
Affected apps: datahub, geoadmin-demo, webcomponents, metadata-editor, demo, map-viewer, search, datafeeder, metadata-converter, data-platform,

• 🚀 Build and deploy storybook and demo on GitHub Pages
• 📦 Build and push affected docker images