Handle finding webmention targets better

If a site does not support webmentions, my code should not error

app/Jobs/SendWebMentions.php

@@ -100,9 +100,12 @@ class SendWebMentions implements ShouldQueue
         } elseif (array_key_exists('http://webmention.org/', $rels[0])) {
             $endpoint = $rels[0]['http://webmention.org/'][0];
         }
-        if ($endpoint) {
+
-            return $this->resolveUri($endpoint, $url);
+        if ($endpoint === null) {
+            return null;
         }
+
+        return $this->resolveUri($endpoint, $url);
     }
 
     /**

tests/Unit/Jobs/SendWebMentionJobTest.php

@@ -109,4 +109,18 @@ class SendWebMentionJobTest extends TestCase
         $job->handle();
         $this->assertTrue(true);
     }
+
+    /** @test */
+    public function linksInNotesCanNotSupportWebmentions(): void
+    {
+        $mock = new MockHandler([
+            new Response(200),
+        ]);
+        $handler = HandlerStack::create($mock);
+        $client = new Client(['handler' => $handler]);
+        $this->app->instance(Client::class, $client);
+
+        $job = new SendWebMentions(new Note());
+        $this->assertNull($job->discoverWebmentionEndpoint('https://example.org'));
+    }
 }