Don't return icons without types at all

lib/REST/Miniflux/V1.php

@@ -814,13 +814,13 @@ class V1 extends \JKingWeb\Arsse\REST\AbstractHandler {
         } catch (ExceptionInput $e) {
             return new ErrorResponse("404", 404);
         }
-        if (!$icon || !$icon['data']) {
+        if (!$icon || !$icon['type'] || !$icon['data']) {
             return new ErrorResponse("404", 404);
         }
         return new Response([
             'id' => $icon['id'],
-            'data' => ($icon['type'] ?: "application/octet-stream").";base64,".base64_encode($icon['data']),
-            'mime_type' => ($icon['type'] ?: "application/octet-stream"),
+            'data' => $icon['type'].";base64,".base64_encode($icon['data']),
+            'mime_type' => $icon['type'],
         ]);
     }
 

tests/cases/REST/Miniflux/TestV1.php

@@ -741,8 +741,8 @@ class TestV1 extends \JKingWeb\Arsse\Test\AbstractTest {
         self::clearData();
         return [
             [['id' => 44, 'type' => "image/svg+xml", 'data' => "<svg/>"], new Response(['id' => 44, 'data' => "image/svg+xml;base64,PHN2Zy8+", 'mime_type' => "image/svg+xml"])],
-            [['id' => 47, 'type' => "",              'data' => "<svg/>"], new Response(['id' => 47, 'data' => "application/octet-stream;base64,PHN2Zy8+", 'mime_type' => "application/octet-stream"])],
-            [['id' => 47, 'type' => null,            'data' => "<svg/>"], new Response(['id' => 47, 'data' => "application/octet-stream;base64,PHN2Zy8+", 'mime_type' => "application/octet-stream"])],
+            [['id' => 47, 'type' => "",              'data' => "<svg/>"], new ErrorResponse("404", 404)],
+            [['id' => 47, 'type' => null,            'data' => "<svg/>"], new ErrorResponse("404", 404)],
             [['id' => 47, 'type' => null,            'data' => null],     new ErrorResponse("404", 404)],
             [null,                                                        new ErrorResponse("404", 404)],
             [new ExceptionInput("subjectMissing"),                        new ErrorResponse("404", 404)],