Report unexpected text in XML sequences in C# (#389)

Currently, we break out of the loop when parsing sequences of
XML elements representing properties of an instances. This gives
misleading error messages ("required property not set").

Instead, with this patch, we report that the text is unexpected, which
is much clearer to the user.

aas_core_codegen/csharp/xmlization/_generate.py

@@ -622,8 +622,25 @@ def _generate_deserialize_impl_cls_from_sequence(
     blocks_for_non_empty.append(
         Stripped(
             f"""\
-while (reader.NodeType == Xml.XmlNodeType.Element)
+while (true)
 {{
+{I}SkipNoneWhitespaceAndComments(reader);
+
+{I}if (reader.NodeType == Xml.XmlNodeType.EndElement || reader.EOF)
+{I}{{
+{II}break;
+{I}}}
+
+{I}if (reader.NodeType != Xml.XmlNodeType.Element)
+{I}{{
+{II}error = new Reporting.Error(
+{III}"Expected an XML start element representing " +
+{III}"a property of an instance of class {name}, " +
+{III}$"but got the node of type {{reader.NodeType}} " +
+{III}$"with the value {{reader.Value}}");
+{II}return null;
+{I}}}
+
 {I}string elementName = TryElementName(
 {II}reader, out error);
 {I}if (error != null)
@@ -682,13 +699,6 @@ def _generate_deserialize_impl_cls_from_sequence(
 {II}}}
 {II}// Skip the expected end element
 {II}reader.Read();
-
-{II}SkipNoneWhitespaceAndComments(reader);
-{I}}}
-
-{I}if (reader.EOF)
-{I}{{
-{II}break;
 {I}}}
 }}"""
         )