System.ArgumentNullException

Value cannot be null. (Parameter 'source')

        public string SourceMessage { get; set; }

        public int? SourceLineNumber => CodeSnippetLines.FirstOrDefault(e => e.IsHighlighted)?.LineNumber;

        public string StackTrace { get; set; }

Solution

In my specific case, I was trying to access an object that was null. So I just added a "?" conditional check to fix the issue.