title: How to get ON CONFLICT IGNORE working in sqlite
body: <p>I'm trying to ignore inserts if a tag and url combo exist already:</p>
  <pre><code>INSERT INTO tags(tag, url) VALUES (?, ?); 
                ON CONFLICT(url, tag) IGNORE 
  </code></pre>
  <p>I have a UNIQUE INDEX on <code>(tag, url)</code></p>
  <pre><code>    CREATE UNIQUE INDEX tag_url ON tags (tag, url)
  </code></pre>
  <p>The app just crashes saying <code>[uncaught application error]: SqliteError - UNIQUE constraint failed: tags.tag, tags.url</code></p>