title: PHP Laravel 5.6 -The Stripe API key is not defined! error message
body: <p>Any help or suggestions will be highly appreciated it!
  I am trying to issue a refund in PHP Laravel 5.6 with Stripe Sandbox Enabled.
  I am using a table and within that table I have two text fields to define the Stripe test and live keys. </p>
  
  <p>This is my services code within PHP Laravel:</p>
  
  <pre><code>
  return [
  
      /*
      |--------------------------------------------------------------------------
      | Third Party Services
      |--------------------------------------------------------------------------
      |
      | This file is for storing the credentials for third party services such
      | as Stripe, Mailgun, SparkPost and others. This file provides a sane
      | default location for this type of information, allowing packages
      | to have a conventional place to find your various credentials.
      |
      */
  
      'mailgun' =&gt; [
          'domain' =&gt; env('MAILGUN_DOMAIN'),
          'secret' =&gt; env('MAILGUN_SECRET'),
      ],
  
      'ses' =&gt; [
          'key' =&gt; env('SES_KEY'),
          'secret' =&gt; env('SES_SECRET'),
          'region' =&gt; 'us-east-1',
      ],
  
      'sparkpost' =&gt; [
          'secret' =&gt; env('SPARKPOST_SECRET'),
      ],
  
      'stripe' =&gt; [
          'model' =&gt; App\User::class,
          'key' =&gt; config('settings.stripe_sandbox_enabled') ? config('settings.stripe_test_key_pk') : config('settings.stripe_live_key_pk'),
          'secret' =&gt; config('settings.stripe_sandbox_enabled') ? config('settings.stripe_test_key_sk') : config('stripe_live_key_sk'),        
      ],
  
  ];
  </code></pre>
  
  <p>Here is the line of code to issue the refund via Stripe in my blade file:</p>
  
  <pre><code>
              //issue refund
              $invoice = $booking-&gt;invoice()-&gt;first();
  
              if($invoice['payment_method'] == __('app.credit_card'))
              {
                  try {
                      //refund via stripe
                      if($booking-&gt;invoice-&gt;is_partial == 1){
                          if($booking-&gt;invoice-&gt;amount_left != 0){
                          //     print_r($booking-&gt;invoice-&gt;transaction_id);
                          // exit();
                              Stripe::refunds()-&gt;create($booking-&gt;invoice-&gt;transaction_id, $booking-&gt;invoice-&gt;first_payment, [
                                  'reason' =&gt; 'requested_by_customer'
                              ]);
                          }
                          else{
                              $transaction_ids = explode(',', $booking-&gt;invoice-&gt;transaction_id);
                              Stripe::refunds()-&gt;create($transaction_ids[0], $booking-&gt;invoice-&gt;first_payment, [
                                      'reason' =&gt; 'requested_by_customer'
                                  ]);
                              Stripe::refunds()-&gt;create($transaction_ids[1], $booking-&gt;invoice-&gt;second_payment, [
                                      'reason' =&gt; 'requested_by_customer'
                                  ]);
                          }
                      }
                      else{
                          Stripe::refunds()-&gt;create($booking-&gt;invoice-&gt;transaction_id, $booking-&gt;invoice-&gt;amount , [
                              'reason' =&gt; 'requested_by_customer'
                          ]);
                      }
  </code></pre>