The Go backend serializes empty slices as JSON null in several places
(e.g. {count:0, topics:null} when no rows match). The SPA assumed
arrays and crashed on .length:
TypeError: Cannot read properties of null (reading 'length')
at Hh (TopicList.tsx:64:45)
Fix in api.ts so every list-returning helper normalizes null → [] once,
centrally. Three call sites covered:
- listTopics — topics field
- listArguments — arguments field
- getAgentSummary — recent_topics field
Components stay as-is; nullable handling moves out of UI code where it
belongs in the data layer. getTopic preserves camps:null vs camps:[]
distinction (null = not yet allocated, [] would be allocated-with-zero
which the allocator contract forbids — keep them meaningfully distinct).
No backend change. Tested on prod with empty topics — list page now
renders 'no topics match this filter' instead of crashing.
hzhang
7dca2c3110