fix: guard formatNumber against non-numeric values (#1721)

## Summary

Fixes #1510

**Root cause:** When a number format (e.g., Percent) is applied to table columns that contain non-numeric values, `formatNumber` doesn't catch non-empty strings. `numbro()` then produces NaN.

The existing check `!value && value !== 0` catches `null`, `undefined`, and `NaN`, but NOT non-empty strings (which are truthy and pass through to `numbro()`).

## Changes

- `packages/app/src/utils.ts`: Added `typeof value !== 'number' || isNaN(value)` guard that returns the raw value as a string instead of formatting it.

## Risk Assessment

**Low** - Only adds a guard for an edge case. Numeric values are formatted exactly as before.

Co-authored-by: Karl Power <85935352+karl-power@users.noreply.github.com>

.changeset/large-seas-clean.md

@@ -0,0 +1,5 @@
+---
+"@hyperdx/app": patch
+---
+
+fix: guard formatNumber against non-numeric values

packages/app/src/__tests__/utils.test.ts

@@ -264,6 +264,23 @@ describe('formatNumber', () => {
       expect(formatNumber(1234567, format)).toBe('1m');
     });
   });
+
+  describe('NaN handling', () => {
+    it('returns "N/A" for NaN without options', () => {
+      expect(formatNumber(NaN)).toBe('N/A');
+      expect(formatNumber(NaN, { output: 'number', mantissa: 2 })).toBe('N/A');
+    });
+
+    it('returns a string unchanged if a number cannot be parsed from it', () => {
+      // @ts-expect-error not passing a number
+      expect(formatNumber('not a number')).toBe('not a number');
+
+      expect(
+        // @ts-expect-error not passing a number
+        formatNumber('not a number', { output: 'number', mantissa: 2 }),
+      ).toBe('not a number');
+    });
+  });
 });
 
 describe('useLocalStorage', () => {

packages/app/src/utils.ts

@@ -760,6 +760,12 @@ export const formatNumber = (
     return 'N/A';
   }
 
+  // Guard against NaN only - ClickHouse can return numbers as strings, which
+  // we should still format. Only truly non-numeric values (NaN) get passed through.
+  if (isNaN(value as number)) {
+    return String(value);
+  }
+
   if (!options) {
     return value.toString();
   }