[YouTube] Move channel header's verified status code to YoutubeChannelHelper

Also throw an exception when we cannot get the verified status of a channel in
YoutubeChannelExtractor due to a missing channelHeader, if the channel has no
channelAgeGateRenderer.

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeChannelHelper.java

@@ -320,4 +320,35 @@ public final class YoutubeChannelHelper {
             return Optional.empty();
         }
     }
+
+    /**
+     * Check if a channel is verified by using its header.
+     *
+     * <p>
+     * The header is mandatory, so the verified status of age-restricted channels with a
+     * {@code channelAgeGateRenderer} cannot be checked.
+     * </p>
+     *
+     * @param channelHeader the {@link ChannelHeader} of a non age-restricted channel
+     * @return whether the channel is verified
+     */
+    public static boolean isChannelVerified(@Nonnull final ChannelHeader channelHeader) {
+        // carouselHeaderRenderer and pageHeaderRenderer does not contain any verification
+        // badges
+        // Since they are only shown on YouTube internal channels or on channels of large
+        // organizations broadcasting live events, we can assume the channel to be verified
+        if (channelHeader.headerType == ChannelHeader.HeaderType.CAROUSEL
+                || channelHeader.headerType == ChannelHeader.HeaderType.PAGE) {
+            return true;
+        }
+
+        if (channelHeader.headerType == ChannelHeader.HeaderType.INTERACTIVE_TABBED) {
+            // If the header has an autoGenerated property, it should mean that the channel has
+            // been auto generated by YouTube: we can assume the channel to be verified in this
+            // case
+            return channelHeader.json.has("autoGenerated");
+        }
+
+        return YoutubeParsingHelper.isVerified(channelHeader.json.getArray("badges"));
+    }
 }

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeChannelExtractor.java

@@ -350,31 +350,12 @@ public class YoutubeChannelExtractor extends ChannelExtractor {
     public boolean isVerified() throws ParsingException {
         assertPageFetched();
         if (channelAgeGateRenderer != null) {
+            // Verified status is unknown with channelAgeGateRenderers, return false in this case
             return false;
         }
 
-        if (channelHeader.isPresent()) {
+        return YoutubeChannelHelper.isChannelVerified(channelHeader.orElseThrow(() ->
-            final ChannelHeader header = channelHeader.get();
+                new ParsingException("Could not get verified status")));
-
-            // carouselHeaderRenderer and pageHeaderRenderer does not contain any verification
-            // badges
-            // Since they are only shown on YouTube internal channels or on channels of large
-            // organizations broadcasting live events, we can assume the channel to be verified
-            if (header.headerType == HeaderType.CAROUSEL || header.headerType == HeaderType.PAGE) {
-                return true;
-            }
-
-            if (header.headerType == HeaderType.INTERACTIVE_TABBED) {
-                // If the header has an autoGenerated property, it should mean that the channel has
-                // been auto generated by YouTube: we can assume the channel to be verified in this
-                // case
-                return header.json.has("autoGenerated");
-            }
-
-            return YoutubeParsingHelper.isVerified(header.json.getArray("badges"));
-        }
-
-        return false;
     }
 
     @Nonnull