channels: handle incomplete auto-generated payloads

spec/invidious/channels/about_spec.cr

@@ -69,7 +69,7 @@ Spectator.describe "extract_auto_generated_channel_header" do
     expect(header[:author_thumbnail]).to eq("//yt3.example/first")
   end
 
-  it "falls back to the ucid when the carousel carries no topic details" do
+  it "raises when the carousel carries no topic details" do
     initdata = JSON.parse(<<-JSON).as_h
       {
         "header": {
@@ -82,10 +82,31 @@ Spectator.describe "extract_auto_generated_channel_header" do
       }
       JSON
 
-    header = extract_auto_generated_channel_header(initdata, "UCEgdi0XIXXZ-qJOFPf4JSKw")
+    expect do
+      extract_auto_generated_channel_header(initdata, "UCEgdi0XIXXZ-qJOFPf4JSKw")
+    end.to raise_error(InfoException)
+  end
 
-    expect(header[:author]).to eq("UCEgdi0XIXXZ-qJOFPf4JSKw")
+  it "raises when the carousel topic details have no title" do
-    expect(header[:author_thumbnail]).to eq("")
+    initdata = JSON.parse(<<-JSON).as_h
+      {
+        "header": {
+          "carouselHeaderRenderer": {
+            "contents": [
+              {
+                "topicChannelDetailsRenderer": {
+                  "avatar": {"thumbnails": [{"url": "//yt3.example/avatar"}]}
+                }
+              }
+            ]
+          }
+        }
+      }
+      JSON
+
+    expect do
+      extract_auto_generated_channel_header(initdata, "UCEgdi0XIXXZ-qJOFPf4JSKw")
+    end.to raise_error(InfoException)
   end
 
   it "parses the current pageHeaderRenderer shape" do

spec/invidious/yt_backend/extractors_spec.cr

@@ -0,0 +1,22 @@
+require "../../parsers_helper"
+
+Spectator.describe "YouTubeTabs" do
+  it "treats a selected tab without content as empty" do
+    initdata = JSON.parse(<<-JSON).as_h
+      {
+        "contents": {
+          "twoColumnBrowseResultsRenderer": {
+            "tabs": [
+              {"tabRenderer": {"selected": true}}
+            ]
+          }
+        }
+      }
+      JSON
+
+    items, continuation = extract_items(initdata)
+
+    expect(items).to be_empty
+    expect(continuation).to be_nil
+  end
+end

src/invidious/channels/about.cr

@@ -75,9 +75,15 @@ def extract_auto_generated_channel_header(initdata : Hash(String, JSON::Any), uc
     # This shape carries neither a banner nor a description.
     details = extract_topic_channel_details(initdata)
 
-    author = details.try &.dig?("title", "simpleText").try &.as_s || ucid
+    unless details
+      raise InfoException.new("Could not extract the carousel header of channel #{ucid}")
+    end
+
+    author = details.dig?("title", "simpleText").try &.as_s
+    author ||= raise InfoException.new("Could not extract the carousel title of channel #{ucid}")
     author_url = "https://www.youtube.com/channel/#{ucid}"
-    author_thumbnail = details.try &.dig?("avatar", "thumbnails", 0, "url").try &.as_s || ""
+    author_thumbnail = details.dig?("avatar", "thumbnails", 0, "url").try &.as_s
+    author_thumbnail ||= raise InfoException.new("Could not extract the carousel thumbnail of channel #{ucid}")
   else
     raise InfoException.new("Could not extract the header of channel #{ucid}")
   end

src/invidious/yt_backend/extractors.cr

@@ -964,7 +964,8 @@ private module Extractors
 
     private def self.extract(target)
       raw_items = [] of JSON::Any
-      content = extract_selected_tab(target["tabs"])["content"]
+      content = extract_selected_tab(target["tabs"])["content"]?
+      return raw_items if content.nil?
 
       if section_list_contents = content.dig?("sectionListRenderer", "contents")
         raw_items = unpack_section_list(section_list_contents)