test: fix spec for topic thumbs

public/openapi/components/schemas/TopicObject.yaml

@@ -5,20 +5,6 @@ TopicObject:
       properties:
         lastposttime:
           type: number
-        thumbs:
-          type: array
-          items:
-            type: object
-            properties:
-              id:
-                type: number
-                description: The topic id
-              name:
-                type: string
-                description: The topic thumbnail filename
-              url:
-                type: string
-                description: Relative path to the topic thumbnail
         category:
           type: object
           properties:
@@ -202,7 +188,8 @@ TopicObject:
         - tid
 TopicObjectSlim:
   description: The output of a call to `Topics.getTopicField`, these properties are always present no matter the fields passed in
-  type: object
+  allOf:
+    - type: object
       properties:
         tid:
           type: number
@@ -265,3 +252,28 @@ TopicObjectSlim:
             - type: number
             - type: string
           nullable: true
+        thumbs:
+          type: array
+          items:
+            type: object
+            properties:
+              id:
+                type: number
+                description: The topic id
+              name:
+                type: string
+                description: The topic thumbnail filename
+              url:
+                type: string
+                description: Relative path to the topic thumbnail
+    - type: object
+      description: Optional properties that may or may not be present (except for `tid`, which is always present, and is only here as a hack to pass validation)
+      properties:
+        tid:
+          type: number
+          description: A topic identifier
+        numThumbs:
+          type: number
+          description: The number of thumbnails associated with this topic
+      required:
+        - tid

public/openapi/read/topic/topic_id.yaml

@@ -46,14 +46,6 @@ get:
                     type: array
                     items:
                       $ref: ../../components/schemas/TagObject.yaml#/TagObject
-                  thumbs:
-                    type: array
-                    items:
-                      type: object
-                      properties:
-                        url:
-                          type: string
-                          description: Relative path to the topic thumbnail
                   posts:
                     type: array
                     items:

public/openapi/read/unread.yaml

@@ -35,14 +35,6 @@ get:
                               nullable: true
                             titleRaw:
                               type: string
-                            thumbs:
-                              type: array
-                              items:
-                                type: object
-                                properties:
-                                  url:
-                                    type: string
-                                    description: Relative path to the topic thumbnail
                             category:
                               type: object
                               properties: