fix: Skip rendering empty SQL dashboard filter (#2115)

## Summary

This PR fixes a bug causing the $__filters macro to error when the dashboard's global SQL filter is an empty string or whitespace only.

### Screenshots or video

Before: an empty string in the SQL filter box would cause $__filters to render as `(())`

<img width="1708" height="1042" alt="Screenshot 2026-04-14 at 1 29 41 PM" src="https://github.com/user-attachments/assets/0a4068ad-eaf2-4bf7-b894-b796f642b59a" />


After: the empty SQL filter is ignored

<img width="2330" height="520" alt="Screenshot 2026-04-14 at 1 29 20 PM" src="https://github.com/user-attachments/assets/a1e83091-5522-4745-b717-f1bf51c84a80" />


### How to test locally or on Vercel

This can be tested in the preview environment

### References



- Linear Issue: Closes HDX-4017
- Related PRs:

Author: pulpdrew

.changeset/sharp-emus-reflect.md

@@ -0,0 +1,5 @@
+---
+"@hyperdx/common-utils": patch
+---
+
+fix: Skip rendering empty SQL dashboard filter

packages/common-utils/src/__tests__/renderChartConfig.test.ts

@@ -1989,6 +1989,25 @@ describe('renderChartConfig', () => {
       );
     });
 
+    it('skips empty sql filters when source has no tableName (metric source)', async () => {
+      const result = await renderChartConfig(
+        {
+          configType: 'sql',
+          sqlTemplate: 'SELECT * FROM logs WHERE $__filters',
+          connection: 'conn-1',
+          dateRange: [start, end],
+          source: 'source-1',
+          from: { databaseName: 'default', tableName: '' },
+          filters: [{ type: 'sql', condition: '' }],
+        },
+        mockMetadata,
+        undefined,
+      );
+      expect(result.sql).toBe(
+        'SELECT * FROM logs WHERE (1=1 /** no filters applied */)',
+      );
+    });
+
     it('skips filters without source metadata (no from)', async () => {
       const result = await renderChartConfig(
         {

packages/common-utils/src/core/renderChartConfig.ts

@@ -1542,7 +1542,9 @@ async function renderFiltersToSql(
         if (filter.type === 'sql_ast') {
           return `(${filter.left} ${filter.operator} ${filter.right})`;
         } else if (filter.type === 'sql' && !hasSourceTable) {
-          return `(${filter.condition})`; // Don't pass to renderWhereExpressionStr since it requires source table metadata
+          return filter.condition.trim()
+            ? `(${filter.condition})` // Don't pass to renderWhereExpressionStr since it requires source table metadata
+            : undefined;
         } else if (
           (filter.type === 'lucene' || filter.type === 'sql') &&
           filter.condition.trim() &&