[fansly] improve file extraction code (#4401)

- add 'format' option
- handle exceptions

test/results/fansly.py

@@ -20,6 +20,40 @@ __tests__ = (
     "#class"   : fansly.FanslyPostExtractor,
 },
 
+{
+    "#url"     : "https://fansly.com/post/545313467469410305",
+    "#comment" : "'This post does not exist or has been deleted.'",
+    "#class"   : fansly.FanslyPostExtractor,
+    "#count"   : 0,
+},
+
+{
+    "#url"     : "https://fansly.com/post/543835794918354944",
+    "#comment" : "one locked image",
+    "#class"   : fansly.FanslyPostExtractor,
+    "#pattern" : r"https://cdn3.fansly.com/364164066794549248/542559086856646656.jpeg\?.+",
+    "#count"   : 1,
+    "#auth"    : False,
+    "#log"     : (
+        "No 'token' provided",
+        "543835794918354944/542560754868432896: Requested format not available",
+    ),
+},
+
+{
+    "#url"     : "https://fansly.com/post/451349524175138816",
+    "#comment" : "locked image + 2 locked videos",
+    "#class"   : fansly.FanslyPostExtractor,
+    "#count"   : 0,
+    "#auth"    : False,
+    "#log"     : (
+        "No 'token' provided",
+        "451349524175138816/451349523013316609: Requested format not available",
+        "451349524175138816/451349523000729600: Requested format not available",
+        "451349524175138816/451349523025899520: Requested format not available",
+    ),
+},
+
 {
     "#url"     : "https://fansly.com/Oliviaus/posts",
     "#class"   : fansly.FanslyCreatorPostsExtractor,