Fix issue with db error

backend/app/server.js

@@ -68,10 +68,13 @@ app.get('/api/line-of-sight', async (req, res) => {
 
     // Bulk land check: use a single query for all points to avoid connection pool exhaustion
     const waterStart = Date.now();
+    const lons = pathPoints.map(p => p.lon);
+    const lats = pathPoints.map(p => p.lat);
+
     const waterCheckQuery = `
       WITH points AS (
-        SELECT i, ST_SetSRID(ST_MakePoint(val[1], val[2]), 4326)::geography as p_geom
-        FROM unnest($1::float8[][]) WITH ORDINALITY AS t(val, i)
+        SELECT i, ST_SetSRID(ST_MakePoint(lon, lat), 4326)::geography as p_geom
+        FROM unnest($1::float8[], $2::float8[]) WITH ORDINALITY AS t(lon, lat, i)
       )
       SELECT i, EXISTS (
         SELECT 1 FROM cities 
@@ -82,8 +85,7 @@ app.get('/api/line-of-sight', async (req, res) => {
       ORDER BY i;
     `;
     
-    const pointsArray = pathPoints.map(p => [p.lon, p.lat]);
-    const waterResults = await pool.query(waterCheckQuery, [pointsArray]);
+    const waterResults = await pool.query(waterCheckQuery, [lons, lats]);
     const waterChecks = waterResults.rows.map(r => !r.has_land);
     
     console.log(`Bulk water check completed in ${Date.now() - waterStart}ms for ${pathPoints.length} points.`);