check if value exists befor using it

[mikkeschiren]

Description:

If no URLs are added to the URL field when creating a new website, you get a warning in the log of missing value for the array $settings['value'].
This suggested patch checks if $settings['value'] exists.

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