Fixes (#435)

* Add flight level field to PIREP field closes #401

* Default value for distance 0 closes #400

* Block airline deletion if assets exist #367

* Formatting

* Move some of the base exception classes

* Fix skin references to use settings table

* Set default for theme name if setting is wrong

tests/AirlineTest.php

@@ -0,0 +1,42 @@
+<?php
+
+use App\Services\AirlineService;
+
+class AirlineTest extends TestCase
+{
+    protected $airlineSvc;
+
+    public function setUp(): void
+    {
+        parent::setUp();
+        $this->addData('base');
+
+        $this->airlineSvc = app(AirlineService::class);
+    }
+
+    /**
+     * Try deleting an airline which has flights/other assets that exist
+     */
+    public function testDeleteAirlineWithFlight()
+    {
+        $airline = factory(App\Models\Airline::class)->create();
+        factory(App\Models\Flight::class)->create([
+            'airline_id' => $airline->id,
+        ]);
+
+        $this->assertFalse($this->airlineSvc->canDeleteAirline($airline));
+    }
+
+    /**
+     * Try deleting an airline with existing PIREPs
+     */
+    public function testDeleteAirlineWithPirep()
+    {
+        $airline = factory(App\Models\Airline::class)->create();
+        factory(App\Models\Pirep::class)->create([
+            'airline_id' => $airline->id,
+        ]);
+
+        $this->assertFalse($this->airlineSvc->canDeleteAirline($airline));
+    }
+}