Process completed with exit code 1.

Nullability of reference types in return type of 'LyricWord? WordMerger.MergeWord(ObservableCollection<LyricLine>? allLines, LyricWord wordToMerge, bool withWordBefore)' doesn't match implicitly implemented member 'LyricWord IWordMerger.MergeWord(ObservableCollection<LyricLine>? allLines, LyricWord wordToMerge, bool withWordBefore)' (possibly because of nullability attributes).

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Possible null reference argument for parameter 'source' in 'bool Enumerable.Any<LyricItem>(IEnumerable<LyricItem> source)'.

Possible null reference argument for parameter 'source' in 'IEnumerable<LyricItem> Enumerable.Where<LyricItem>(IEnumerable<LyricItem> source, Func<LyricItem, bool> predicate)'.

This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.

Converting null literal or possible null value to non-nullable type.

Dereference of a possibly null reference.

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.