From 9c440ca105e3a0108586a81d75b49a3d789d7ed0 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Tue, 16 May 2023 14:37:31 -0700
Subject: [PATCH] Guard against URIs (not QNames) being used for tags.

---
 lib/rdf/rdfxml/writer.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/rdf/rdfxml/writer.rb b/lib/rdf/rdfxml/writer.rb
index 7fb27f7..b7f11e5 100644
--- a/lib/rdf/rdfxml/writer.rb
+++ b/lib/rdf/rdfxml/writer.rb
@@ -259,6 +259,7 @@ def render_subject(subject, builder, **options, &block)
       # The first type is used for
       first_type = types.shift
       type_qname = get_qname(first_type) if first_type
+      type_qname = nil unless type_qname.is_a?(String)
       types.unshift(first_type) if first_type && !type_qname
       type_qname ||= "rdf:Description"
 
@@ -619,7 +620,7 @@ def expand_curie(curie)
     # Turn CURIE into a QNAME or return the RDF::URI
     def get_qname(uri)
       curie = get_curie(uri)
-      if curie.nil?
+      if curie.nil? || curie == ':'
         uri
       elsif curie.start_with?(":")
         curie[1..-1]