fix bug with invalid slug

Author: balping

src/HasHashSlug.php

@@ -113,14 +113,18 @@ public function resolveRouteBinding($slug){
 	/**
 	 * Decodes slug to id
 	 * @param  string $slug
-	 * @return int
+	 * @return int|null
 	 */
 	private static function decodeSlug($slug){
 		$hashids = static::getHashids();
 
-		$id = (int) $hashids->decode($slug)[0];
+		$decoded = $hashids->decode($slug);
 
-		return $id;
+		if(! isset($decoded[0])){
+			return null;
+		}
+
+		return (int) $decoded[0];
 	}
 
 	/**
@@ -139,7 +143,7 @@ public static function findBySlugOrFail($slug){
 	 * Wrapper around Model::find
 	 * 
 	 * @param  string $slug
-	 * @return \Illuminate\Database\Eloquent\Model
+	 * @return \Illuminate\Database\Eloquent\Model|null
 	 */
 	public static function findBySlug($slug){
 		$id = static::decodeSlug($slug);

tests/HashSlugTest.php

@@ -89,6 +89,17 @@ public function model_can_be_found_by_slug(){
 		$this->assertEquals($post->id, $foundPost->id);
 	}
 
+	/** @test */
+	public function find_byinvalid_slug_returns_null(){
+		$post = Post::forceCreate(["title" => "title1"]);
+
+		$slug = 'XX' . $post->slug();
+
+		$foundPost = Post::findBySlug($slug);
+
+		$this->assertNull($foundPost);
+	}
+
 	/** @test */
 	public function slugs_are_different_for_same_id_but_different_model(){
 		$post = Post::forceCreate(["title" => "title1"]);