Fatal error: Uncaught TypeError: mb_strpos(): Argument #1 ($haystack) must be of type string, null given,

My application has been working for months without fault. Last week I changed a few formatting things within a blade file, and today I get this error. I have no clue where to start with this as none of the logic within the controllers of models was changed just the one blade file. Here is the full error, which I pulled off my dev machine. Any ideas anyone? Many thanks !!

Fatal error: Uncaught TypeError: mb_strpos(): Argument #1 ($haystack) must be of type string, null given, called in C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Support\Str.php on line 183 and defined in C:\laragon\www\KidsClub\vendor\symfony\polyfill-mbstring\bootstrap80.php:60 Stack trace: #0 C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Support\Str.php(183): mb_strpos(NULL, '/json') #1 C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Http\Concerns\InteractsWithContentTypes.php(16): Illuminate\Support\Str::contains(NULL, Array) #2 C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Http\Request.php(371): Illuminate\Http\Request->isJson() #3 C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Http\Request.php(435): Illuminate\Http\Request->getInputSource() #4 C:\laragon\www\KidsClub\vendor\laravel\framework\src\Illuminate\Http\Request.php(64): Illuminate\Http\Request::createFromBase(Object(Symfony\Component\HttpFoundation\Request)) #5 C:\laragon\www\KidsClub\public\index.php(55): Illuminate\Http\Request::capture() #6 {main} thrown in C:\laragon\www\KidsClub\vendor\symfony\polyfill-mbstring\bootstrap80.php on line 60