Add support for unlisted posts

DanbooruApi.own

@@ -1,6 +1,7 @@
 use okhttp, types, json, functional
 
 URL = "https://danbooru.donmai.us/posts"
+NO_IMAGE = "https://upload.wikimedia.org/wikipedia/commons/1/14/No_Image_Available.jpg"
 
 class DanbooruApi {
 
@@ -68,12 +69,12 @@ class Post {
   def getImageUrl() {
     fileSize = this.post.file_size ?? 0
     if (fileSize >= 9500000) {
-      return this.post.large_file_url
+      return this.post.large_file_url ?? NO_IMAGE
     }
-    return this.post.file_url
+    return this.post.file_url ?? NO_IMAGE
   }
 
-  def getSampleImageUrl() = this.post.large_file_url
+  def getSampleImageUrl() = this.post.large_file_url ?? NO_IMAGE
 
   def containsTags(tags) = stream(tags)
     .anyMatch(def(t) = arrayKeyExists(t, this.tags))

bot.own

@@ -56,7 +56,7 @@ def processPost(id, chatId, msgId, from) {
   ]})
   bot.invoke("sendPhoto", {
     "chat_id": chatId,
-    "photo": post.getImageUrl(),
+    "photo": post.getImageUrl()
     "parse_mode": "html",
     "caption": caption,
     "reply_markup": markup
@@ -68,7 +68,7 @@ def processPost(id, chatId, msgId, from) {
     if !r.contains("wrong file identifier") return 1
     bot.invoke("sendPhoto", {
       "chat_id": chatId,
-      "photo": post.getSampleImageUrl(),
+      "photo": post.getSampleImageUrl()
       "parse_mode": "html",
       "caption": "small " + caption,
       "reply_markup": markup