Error: array_merge(): Expected parameter 2 to be an array, int given

Laravel 8 throws me the error array_merge(): Expected parameter 2 to be an array, int given when updating a record in the database. However, if you update the registry and I don't see where the problem is. I leave you the code to see if you can tell me what the problem is.

Controller:

try {
        $showclient = Client::findOrfail($id);
        
        $showclient->update(
            [
                'cif'  =>  $request->cif,
                'company'   =>  $request->company,
                'corporateaddress'  =>  $request->corporateaddress,
                'postalcode'    =>  $request->postalcode,
                'locality'  =>  $request->locality,
                'province'  =>  $request->province,
                'telephone' =>  $request->telephone,
                'mobile'    =>  $request->mobile,
                'type'  =>  $request->type,
                'contactname'   =>  $request->contactname,
                'telephonecontact'  =>  $request->telephonecontact,
                'mobilecontact' =>  $request->mobilecontact,
                'emailcontact'  =>  $request->emailcontact,
            ]
        );

        Log::info(
            '¡¡CLIENTE ACTUALIZADO!!. 
            Actualizados los datos del cliente con ID: '
            . $request->id
        );

        return view('admin.clients.show', $showclient->id)->with(
            'success', 
            'Los datos del cliente indicado han sido actualizados correctamente.'
        );
    } catch (\Throwable $th) {
        Log::error(
            '¡¡ERROR EN ACTUALIZACIÓN DE CLIENTE!!, Operación Cancelada. 
            Mensaje de error:' . $th->getMessage()
        );
        
        return redirect()->route('admin.clients.index')->with(
            'error', 'Error en el proceso de actualización. 
            Contacte con el administrador del sistema. Error: '
            . $th->getMessage()
        );
    }

Thanks in advance, regards.