Enhance search.js with Error Handling and Input Validation

[mahdiatubly]

Error Resilience:
Added error handling to the fetch call to ensure the application gracefully handles failed network requests or server errors.
Provided validation for searchTerm to prevent potential runtime issues caused by invalid inputs.

Robustness:
Ensured the data-search-url attribute is present before initiating the request, preventing unexpected crashes.

Modern JavaScript Practices:
Updated the code for readability and maintainability using optional chaining, descriptive error messages, and streamlined error propagation.

Backward Compatibility:
The changes preserve the current behavior while improving error reporting and debugging for developers.

Alignment with Contribution Goals:
The enhancements aim to improve the user experience and maintain a high-quality codebase, aligning with the Jenkins open-source community's standards.

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[janfaracik]

Hey, thanks for this and welcome to the community!

This function is only used internally in Jenkins (and only in one place) so I don't think we really benefit from the added error handling, e.g. there shouldn't be a reason as to why buttonElement?.dataset?.searchUrl is null/undefined. As for the fetch() error catching, we could probably handle this more gracefully than we do (e.g. we don't currently) but I think it'd be such a rare use case it's not worth it.