stripos null user agent warning

[wussup]

stripos can not take a null value as an argument in PHP 8.1+

Deprecated: strpos(): Passing null to parameter #1 ($haystack)

Summary of Changes

check $userAgent before use stripos() function

Testing Instructions

make GET request without User Agent header

Documentation Changes Required

nothing

[rdeutz]

Thanks for the PR.

Sorry for the delay in replying:

• Please fix the code style issues
• It would be better to make an early return when the $userAgent is empty, moving "$this->detection['engine'] = true;" to the top of the functions is fine
• Please make the change for all detect functions.

[Quy]

Alternative PR #131

[Hackwar]

Thank you for proposing this. As @Quy provided a better alternative, we are going with that one. Because of that, I'm closing this one. Thank you for your time.