Fix sources template rendering

tests/test_templates.py

@@ -0,0 +1,12 @@
+from pathlib import Path
+
+
+def test_templates_do_not_slice_filter_results_inline():
+    template_dir = Path("webui/app/templates")
+    offenders = []
+    for template in template_dir.glob("*.html"):
+        content = template.read_text()
+        if "| default(" in content and ")[" in content:
+            offenders.append(str(template))
+
+    assert offenders == []