feat(stats): add v1 immersion stats dashboard (#19)

stats/src/hooks/useSessions.test.ts

@@ -0,0 +1,20 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import test from 'node:test';
+import { fileURLToPath } from 'node:url';
+import { toErrorMessage } from './useSessions';
+
+const USE_SESSIONS_PATH = fileURLToPath(new URL('./useSessions.ts', import.meta.url));
+
+test('toErrorMessage normalizes Error and non-Error rejections', () => {
+  assert.equal(toErrorMessage(new Error('network down')), 'network down');
+  assert.equal(toErrorMessage('bad gateway'), 'bad gateway');
+  assert.equal(toErrorMessage(503), '503');
+});
+
+test('useSessions and useSessionDetail route catch handlers through toErrorMessage', () => {
+  const source = fs.readFileSync(USE_SESSIONS_PATH, 'utf8');
+  const matches = source.match(/setError\(toErrorMessage\(err\)\)/g);
+
+  assert.equal(matches?.length, 2);
+});