nip23: the renderer is not goroutine-safe so it can't be reused.

nip23/markdown.go

@@ -15,7 +15,8 @@ import (
 
 var nostrEveryMatcher = regexp.MustCompile(`nostr:((npub|note|nevent|nprofile|naddr)1[a-z0-9]+)\b`)
 
-var renderer = html.NewRenderer(html.RendererOptions{
+func MarkdownToHTML(md string) string {
+	renderer := html.NewRenderer(html.RendererOptions{
 		Flags: html.HrefTargetBlank | html.SkipHTML,
 		RenderNodeHook: func(w io.Writer, node ast.Node, entering bool) (ast.WalkStatus, bool) {
 			switch v := node.(type) {
@@ -29,9 +30,8 @@ var renderer = html.NewRenderer(html.RendererOptions{
 
 			return ast.GoToNext, false
 		},
-})
+	})
 
-func MarkdownToHTML(md string) string {
 	md = strings.ReplaceAll(md, "\u00A0", " ")
 
 	// create markdown parser with extensions