Indent filter crashes when passed unexpected input

I've found that the indent filter will crash Nunjucks if not passed a string.

Minimal test case:

{% set testArray = ['one', 'two'] %}

{# Crashes #}
{{ testArray | indent(8) }}

The error returned is str.split is not a function

Why I think this is a bug

My general expectation with Nunjucks is that it fails gracefully. Usually if something isn't as expected it displays nothing and continues to render.

What I might have expected

I think I would have expected it to do one of:

• don't do anything - return original input
• don't do anything - return null / false / undefined
• cast to string and then indent

This isn't an issue for my project as I was only temporarily rendering it to check progress as I go. Many of our components use indent filter behind the scenes. I'll be updating the nunjucks to iterate over the array for display anyway.