CLOUD-2557 Ensure only strings are decoded by Twig filter

[marcel-innocraft]

Description:

When rendering DataTables returned via the ProxySite plugin, it's possible that some columns contain arrays. The template calls the addFilterSafeDecodeRaw() method for each column within the result set and will trigger the following PHP exception if the column contains a non-scalar value:

An exception has been thrown during the rendering of a template ("urldecode(): Argument #1 ($string) must be of type string, array given").

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed

[michalkleiner]

@marcel-innocraft I think it might be more valuable to identify the cases where the column becomes an array to resolve those. Would you have any insights on that?

[marcel-innocraft]

@marcel-innocraft I think it might be more valuable to identify the cases where the column becomes an array to resolve those. Would you have any insights on that?

I initially wanted to fix the issue at the source as well, but I believe the error is only occurring when URLs are manually crafted to populate additional visitor data such as actionDetails (an array) - so I don't think that data is something we normally render as part of a report. It's also possible for plugins to populate columns with arrays via the API.Live.getLastVisitsDetails event, which present more opportunities for the error to be triggered.

The solution in this PR will blank out any non-scalar values the renderer encounters, which means the values are indistinguishable from actual blank values, so this was a draft while I was considering alternative ways to handle it. The options are fairly limited though.

[sgiehl]

@marcel-innocraft Would it be worth to at least add some logging when non scalar values occur? Otherwise we might hide some real bugs we do not discover anymore 🤔

[marcel-innocraft]

Given this is a rare error and that when it happens then we are logging it appropriately, I think it's best to close this off and we'll deal with any occurrences if/when they arise.