fix: handle tables with no properties

src/scripts/get_tile.sql

@@ -1,14 +1,7 @@
 WITH bounds AS (SELECT {mercator_bounds} as mercator, {original_bounds} as original)
 SELECT ST_AsMVT(tile, '{id}', {extent}, 'geom') FROM (
   SELECT
-    ST_AsMVTGeom(
-      {geometry_column_mercator},
-      bounds.mercator,
-      {extent},
-      {buffer},
-      {clip_geom}
-    ) AS geom,
-    {properties}
+    ST_AsMVTGeom({geometry_column_mercator}, bounds.mercator, {extent}, {buffer}, {clip_geom}) AS geom {properties}
   FROM {id}, bounds
   WHERE {geometry_column} && bounds.original {condition}
 ) AS tile WHERE geom IS NOT NULL

src/source.rs

@@ -41,12 +41,17 @@ impl Source {
             )
         };
 
-        let columns: Vec<String> = self.properties
-            .keys()
-            .map(|column| format!("\"{0}\"", column))
-            .collect();
+        let properties = if self.properties.is_empty() {
+            "".to_string()
+        } else {
+            let properties = self.properties
+                .keys()
+                .map(|column| format!("\"{0}\"", column))
+                .collect::<Vec<String>>()
+                .join(",");
 
-        let properties = columns.join(",");
+            format!(", {0}", properties)
+        };
 
         let query = format!(
             include_str!("scripts/get_tile.sql"),