Fixed passing invalid argument to strpos()

[marcusmoore]

Description

I noticed a couple tests failing when run on PHP 7.4 due to an empty string being passed as the second parameter to strpos() which isn't valid pre-8.0.

This small PR moves the existing $prefix == '' up so calling strpos is skipped if the prefix is an empty string.

@uberbrady can you double-check this makes sense please?

Type of change

• Bug fix (non-breaking change which fixes an issue)

[what-the-diff]

PR Summary

• Improved Asset Creation Procedure in AssetObserver.php
  We have modified the 'created' method logic in AssetObserver.php to ensure a better asset creation process. Now it checks if the 'auto_increment_assets' option is activated and if the prefix accurately matches the start of the tag. This change also accommodates cases where there might be no prefix. This should improve the reliability and accuracy of automatic asset creation.

[uberbrady]

Very elegant and clean fix, makes total sense to me! Great catch!