Properly handle songs with only English title

src/utils/furigana.rs

@@ -16,6 +16,9 @@ pub fn furigana_to_html(text: &str) -> String {
 }
 
 pub fn furigana_filter(value: &Value, _args: &HashMap<String, Value>) -> tera::Result<Value> {
+    if value.is_null() {
+        return Ok(Value::String("".to_string()));
+    }
     Ok(Value::String(furigana_to_html(value.as_str().expect("The furigana input must be a string"))))
 }
 

templates/index.html.tera

@@ -19,7 +19,7 @@
             <a class="link" href="/{{ challenge + 1 }}"><svg class="svg-inline" aria-hidden="true" focusable="false" role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 384 512"><path fill="currentColor" d="M342.6 233.4c12.5 12.5 12.5 32.8 0 45.3l-192 192c-12.5 12.5-32.8 12.5-45.3 0s-12.5-32.8 0-45.3L274.7 256 105.4 86.6c-12.5-12.5-12.5-32.8 0-45.3s32.8-12.5 45.3 0l192 192z"></path></svg></a>
             {% if content.song %}
             <div>
-                <span>{{ content.song.japanese }}</span>
+                <span>{% if content.song.japanese %}{{ content.song.japanese | furigana | safe }}{% else %}{{ content.song.english }}{% endif %}</span>
             </div>
             {% endif %}
             {% if user %}