[gnome-builder] html: handle empty element name

[Christian Hergert <chergert src gnome org>]

commit 96c2f7154daa11d494d3ec4f4e9c43d5c71f4e92
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 9 02:41:36 2018 -0700

    html: handle empty element name
    
    Fixes #530

 src/plugins/html-completion/ide-html-completion-provider.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/plugins/html-completion/ide-html-completion-provider.c 
b/src/plugins/html-completion/ide-html-completion-provider.c
index 2c029fd8e..ba00b39c3 100644
--- a/src/plugins/html-completion/ide-html-completion-provider.c
+++ b/src/plugins/html-completion/ide-html-completion-provider.c
@@ -260,7 +260,8 @@ whereami (IdeCompletionContext  *context,
       break;
 
     case IDE_HTML_PROPOSAL_ATTRIBUTE_NAME:
-      *element = get_element (&begin);
+      if (!(*element = get_element (&begin)))
+        *kind = IDE_HTML_PROPOSAL_NONE;
       break;
 
     case IDE_HTML_PROPOSAL_NONE: