Friendly Wrap now silently breaks when passing null value

The recent update to remove v-html from the friendly wrap caused a bug where if you pass a null value to the component it breaks the page. This is due to the line in src/utils/string_utils.js where we check if the string length is equal to 0.

An example of the issue is this bug report for the pipeline test report.

Proposal

I think it's fine that we don't allow null values, but perhaps we can make it more clear in props validation. Or we could default the prop to an empty string.