Laravel - firstOrCreate() detects argument 1 as non-array, but it is - php

Question

I have the following code:
$coretable = new coretable;
$coretableKeyArray = [];
$coretableKeyArray["Internal_key"] = $coretableInput["Internal_key"];
if(is_array($coretableKeyArray)){
log::info("recognized as array");
}
$lastInsert = $coretable->firstOrCreate($coretableKeyArray, $coretableInput);
The array for argument 1 of firstOrCreate() looks like this:
[2020-02-27 07:30:50] local.INFO: array (
'Internal_key' => 'TESTKEY_4',
)
the is_array() also returns true on $coretableKeyArray
However, when doing the call to firstOrCreate() here:
$lastInsert = $coretable->firstOrCreate($coretableKeyArray, $coretableInput);
I get this error:
(1/1) TypeError
Argument 1 passed to Illuminate\Database\Eloquent\Builder::firstOrCreate() must be of the type array, int given, called in E:\aether-backend\vendor\illuminate\support\Traits\ForwardsCalls.php on line 23
in Builder.php line 415
at Builder->firstOrCreate(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4'))in ForwardsCalls.php line 23
at Model->forwardCallTo(object(Builder), 'firstOrCreate', array(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4')))in Model.php line 1618
at Model->__call('firstOrCreate', array(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4')))in modelInteractions.php line 128
Why is that? Also, why does the log of the error show me:
Builder->firstOrCreate(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4'))
Why is the first argument "4" here? What does it represent? Because it cant represent the value of the first argument of the call to firstOrCreate() because that was an entirely different one...
EDIT:
Here is the full errorstack, as requested per comment:
(1/1) TypeError
Argument 1 passed to Illuminate\Database\Eloquent\Builder::firstOrCreate() must be of the type array, int given, called in E:\aether-backend\vendor\illuminate\support\Traits\ForwardsCalls.php on line 23
in Builder.php line 415
at Builder->firstOrCreate(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4'))in ForwardsCalls.php line 23
at Model->forwardCallTo(object(Builder), 'firstOrCreate', array(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4')))in Model.php line 1618
at Model->__call('firstOrCreate', array(4, array('coretable_id' => 4, 'description_itc' => 'EXTENSION_ITC_4')))in modelInteractions.php line 127
at modelInteractions->insertModel(array('Internal_key' => 'TESTKEY_4'), array('Internal_key' => 'TESTKEY_4', 'extensiontable_itc' => array('description_itc' => 'EXTENSION_ITC_4'), 'extensiontable_sysops' => array('description_sysops' => 'EXTENSION_SYSOPS_4')), array('extensiontable_itc', 'extensiontable_sysops'))in UserController.php line 100
at UserController->insertDataCreateNewItem(object(Request))
at call_user_func_array(array(object(UserController), 'insertDataCreateNewItem'), array(object(Request)))in BoundMethod.php line 32
at BoundMethod::Illuminate\Container\{closure}()in Util.php line 36
at Util::unwrapIfClosure(object(Closure))in BoundMethod.php line 90
at BoundMethod::callBoundMethod(object(Application), array(object(UserController), 'insertDataCreateNewItem'), object(Closure))in BoundMethod.php line 34
at BoundMethod::call(object(Application), array(object(UserController), 'insertDataCreateNewItem'), array(), null)in Container.php line 590
at Container->call(array(object(UserController), 'insertDataCreateNewItem'), array())in RoutesRequests.php line 376
at Application->callControllerCallable(array(object(UserController), 'insertDataCreateNewItem'), array())in RoutesRequests.php line 342
at Application->callLumenController(object(UserController), 'insertDataCreateNewItem', array(true, array('uses' => 'App\\Http\\Controllers\\UserController#insertDataCreateNewItem', 'middleware' => array('auth')), array()))in RoutesRequests.php line 316
at Application->callControllerAction(array(true, array('uses' => 'App\\Http\\Controllers\\UserController#insertDataCreateNewItem', 'middleware' => array('auth')), array()))in RoutesRequests.php line 278
at Application->callActionOnArrayBasedRoute(array(true, array('uses' => 'App\\Http\\Controllers\\UserController#insertDataCreateNewItem', 'middleware' => array('auth')), array()))in RoutesRequests.php line 258
at Application->Laravel\Lumen\Concerns\{closure}(object(Request))
at call_user_func(object(Closure), object(Request))in Pipeline.php line 52
at Pipeline->Laravel\Lumen\Routing\{closure}(object(Request))in Authenticate.php line 36
at Authenticate->handle(object(Request), object(Closure))in Pipeline.php line 171
at Pipeline->Illuminate\Pipeline\{closure}(object(Request))
at call_user_func(object(Closure), object(Request))in Pipeline.php line 32
at Pipeline->Laravel\Lumen\Routing\{closure}(object(Request))in Pipeline.php line 105
at Pipeline->then(object(Closure))in RoutesRequests.php line 413
at Application->sendThroughPipeline(array('App\\Http\\Middleware\\Authenticate'), object(Closure))in RoutesRequests.php line 259
at Application->handleFoundRoute(array(true, array('uses' => 'App\\Http\\Controllers\\UserController#insertDataCreateNewItem', 'middleware' => array('auth')), array()))in RoutesRequests.php line 165
at Application->Laravel\Lumen\Concerns\{closure}(object(Request))
at call_user_func(object(Closure), object(Request))in Pipeline.php line 52
at Pipeline->Laravel\Lumen\Routing\{closure}(object(Request))in CORS.php line 34
at CORS->handle(object(Request), object(Closure))in Pipeline.php line 171
at Pipeline->Illuminate\Pipeline\{closure}(object(Request))
at call_user_func(object(Closure), object(Request))in Pipeline.php line 32
at Pipeline->Laravel\Lumen\Routing\{closure}(object(Request))in Pipeline.php line 105
at Pipeline->then(object(Closure))in RoutesRequests.php line 413
at Application->sendThroughPipeline(array('App\\Http\\Middleware\\CORS'), object(Closure))in RoutesRequests.php line 171
at Application->dispatch(null)in RoutesRequests.php line 108
at Application->run()in index.php line 28
EDIT:
Question can be closed or deleted, the solution to the problem was somewhere else.

Answer 1

Try this:
$lastInsert = $coretable->firstOrCreate((array)$coretableKeyArray, $coretableInput);
If that doesn't work, in case you've overloaded firstOrCreate make sure it doesn't do custom casts within it.

Answer 2

Instead of storing in a variable you can directly put it in the method.
Much cleaner and also readable.
$coretable->firstOrCreate([
'Internal_key' => $coretableInput["Internal_key"]
], $coretableInput);