FIO-8993: Fixed component validation message

[roma-formio]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8993

Description

Issue: The message variable can be either a single string or an array of strings. When message is a single string, using message[0] incorrectly accesses the first character of the string instead of the intended first element of an array.

Solution: Add a check to determine if message is an array or a single string before accessing its elements.

Checklist:

• I have completed the above PR template
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above