Checked whether block comments actually have paragraphs.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/Core/Parser/ASTConverter.cs

@@ -1752,6 +1752,7 @@ namespace CppSharp
         private void VisitBlockCommandComment(AST.BlockCommandComment blockCommandComment, BlockCommandComment comment)
         {
             blockCommandComment.CommandId = comment.CommandId;
+            if (comment.ParagraphComment != null)
                 blockCommandComment.ParagraphComment = (AST.ParagraphComment) Visit(comment.ParagraphComment);
             for (uint i = 0; i < comment.ArgumentsCount; i++)
             {

src/Generator/Generators/CSharp/CSharpCommentPrinter.cs

@@ -29,7 +29,8 @@ namespace CppSharp.Generators.CSharp
                     break;
                 case CommentKind.BlockCommandComment:
                     var blockCommandComment = (BlockCommandComment) comment;
-                    if (blockCommandComment.CommandKind == CommentCommandKind.Return)
+                    if (blockCommandComment.CommandKind == CommentCommandKind.Return &&
+                        blockCommandComment.ParagraphComment != null)
                     {
                         sections.Add(new Section(CommentElement.Returns));
                         blockCommandComment.ParagraphComment.GetCommentSections(sections);
@@ -42,6 +43,7 @@ namespace CppSharp.Generators.CSharp
                     if (paramCommandComment.Arguments.Count > 0)
                         param.Attributes.Add(
                             string.Format("name=\"{0}\"", paramCommandComment.Arguments[0].Text));
+                    if (paramCommandComment.ParagraphComment != null)
                         foreach (var inlineContentComment in paramCommandComment.ParagraphComment.Content)
                             inlineContentComment.GetCommentSections(sections);
                     break;