fix(stemming): handle null response from dictionary retrieval

- add null check in `StemmingDictionaries::retrieve()` to return empty dict
- add setup method to initialize dictionary before tests
- fix typo in test method name from `Rules` to `Dictionaries`

Author: tharropoulos

src/StemmingDictionaries.php

@@ -47,7 +47,13 @@ static function ($item) {
 
     public function retrieve()
     {
-        return $this->apiCall->get(StemmingDictionaries::RESOURCE_PATH, []);
+        $response = $this->apiCall->get(StemmingDictionaries::RESOURCE_PATH, []);
+
+        // If response is null, return empty dictionaries structure
+        if ($response === null) {
+            return ['dictionaries' => []];
+        }
+        return $response;
     }
 
     private function endpoint_path($operation = null)

tests/Feature/StemmingDictionariesTest.php

@@ -15,6 +15,16 @@ class StemmingDictionariesTest extends TestCase
 
     private $dictionaryUpsertResponse = null;
 
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->client()->stemming->dictionaries()->upsert(
+            $this->dictionaryId, 
+            $this->dictionary
+        );
+    }
+
     public function testCanUpsertADictionary(): void
     {
         $this->dictionaryUpsertResponse = $this->client()->stemming->dictionaries()->upsert($this->dictionaryId, $this->dictionary);
@@ -28,7 +38,7 @@ public function testCanRetrieveADictionary(): void
     }
 
 
-    public function testCanRetrieveAllRules(): void
+    public function testCanRetrieveAllDicitionaries(): void
     {
         $returnData = $this->client()->stemming->dictionaries()->retrieve();
         $this->assertCount(1, $returnData['dictionaries']);