Add configuration options

templates/empty.html

@@ -1,2 +1,14 @@
 <p>There are no nodes. The graph is either empty or failed to parse.</p>
-<p>Check the <a href="/graph/toml">raw endpoints</a> for possible parsing errors.</p>
+{% if config.raw %}
+<p>Check the
+    {% if config.raw_toml %}
+    <a href="/graph/toml">
+    {% elif config.raw_json %}
+    <a href="/graph/json">
+    {% endif %}
+        raw endpoints
+    {% if config.raw_toml or config.raw_json %}
+    </a>
+    {% endif %}
+    for possible parsing errors.</p>
+{% endif %}