fix(ui): Handle null/undefined span.description safely (#1239)

## Summary

Fix runtime error when calling `.trim()` on non-string
`span.description` values.

## Root Cause

The `Span.description` property is typed as `string | null | undefined`.
The previous code used `String(span?.description).trim()` which
converts:
- `null` → `"null"` (literal string)
- `undefined` → `"undefined"` (literal string)

These incorrect values passed through the `.delete("")` cleanup and
appeared as valid queries/resources.

## Fix

Use nullish coalescing (`??`) to return an empty string for
`null`/`undefined`, which the existing cleanup handles correctly:

```typescript
// Before
String(span?.description).trim()

// After
(span.description ?? "").trim()
```

Fixes SPOTLIGHT-ELECTRON-4V

Author: BYK

packages/spotlight/src/ui/telemetry/components/insights/Queries.tsx

@@ -51,7 +51,7 @@ const Queries = () => {
     const compareQueryInfo = COMPARATORS[sort.active] || COMPARATORS[QUERIES_SORT_KEYS.totalTime];
     const spans = allSpans;
     const onlyDBSpans = spans.filter((span: Span) => DB_SPAN_REGEX.test(span.op || ""));
-    const uniqueSpansSet = new Set(onlyDBSpans.map(span => String(span?.description).trim()));
+    const uniqueSpansSet = new Set(onlyDBSpans.map(span => (span.description ?? "").trim()));
     // Clear out empty ones (they collapse as a single empty string since this is a set)
     uniqueSpansSet.delete("");
     return [...uniqueSpansSet]

packages/spotlight/src/ui/telemetry/components/insights/Resources.tsx

@@ -73,7 +73,7 @@ const Resources = () => {
 
   const resources = useMemo(() => {
     const filteredResourceSpans = getResourceSpans(allSpans, { regex: /resource\.[A-Za-z]+/ });
-    const uniqueResourceDescriptionsSet = new Set(filteredResourceSpans.map(span => String(span?.description).trim()));
+    const uniqueResourceDescriptionsSet = new Set(filteredResourceSpans.map(span => (span.description ?? "").trim()));
     // Clear out empty ones (they collapse as a single empty string since this is a set)
     uniqueResourceDescriptionsSet.delete("");
     const uniqueResourceDescriptions: string[] = [...uniqueResourceDescriptionsSet];