AURORA: Throw on GFF4 with shared string and ASCII string fields

We have no example GFF4 file with shared strings and ASCII string
fields, so we don't know whether these fields use the shared string
table.

src/aurora/gff4file.cpp

@@ -411,6 +411,9 @@ void GFF4Struct::load(GFF4File &parent, uint32 offset, const GFF4File::StructTem
 			loadStructs(parent, f);
 		if (f.type == kFieldTypeGeneric)
 			loadGeneric(parent, f);
+
+		if ((f.type == kFieldTypeASCIIString) && parent.hasSharedStrings())
+			throw Common::Exception("GFF4: TODO: ASCII string field in a file with shared strings");
 	}
 
 	_fieldCount = _fields.size();
@@ -508,6 +511,9 @@ void GFF4Struct::load(GFF4File &parent, const Field &genericParent) {
 			loadStructs(parent, f);
 		if (f.type == kFieldTypeGeneric)
 			throw Common::Exception("GFF4: Found a generic with type generic?");
+
+		if ((f.type == kFieldTypeASCIIString) && parent.hasSharedStrings())
+			throw Common::Exception("GFF4: TODO: ASCII string field in a file with shared strings");
 	}
 
 	_fieldCount = genericCount;