Fix null pointer exception

Author: chowder

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

@@ -350,10 +350,10 @@ public boolean isShortFormContent() throws ParsingException {
                         .orElse(null);
 
                 if (!isNullOrEmpty(thumbnailTimeOverlay)) {
-                    isShort = thumbnailTimeOverlay.getString("style")
+                    isShort = thumbnailTimeOverlay.getString("style", "")
                             .equalsIgnoreCase("SHORTS")
                             || thumbnailTimeOverlay.getObject("icon")
-                            .getString("iconType")
+                            .getString("iconType", "")
                             .toLowerCase()
                             .contains("shorts");
                 }