Add an example and fix the bug

Author: rojvv

example.deno.ts

@@ -0,0 +1,18 @@
+// Run with `deno run --unstable-ffi -A example.deno.ts`
+import { query, Session } from "./mod.ts";
+
+// Create a new session instance
+const session = new Session("./chdb-bun-tmp");
+let result;
+
+// Test standalone query
+result = query("SELECT version(), 'Hello chDB', chdb()", "CSV");
+console.log(result);
+
+// Test session query
+session.query("CREATE FUNCTION IF NOT EXISTS hello AS () -> 'chDB'", "CSV");
+result = session.query("SELECT hello()", "CSV");
+console.log(result);
+
+// Clean up the session
+session.cleanup();

mod.ts

@@ -34,11 +34,15 @@ class Session {
 
   query(query: string, format: string = "CSV") {
     if (!query) return "";
-    return chdb.QuerySession(
+    const result = chdb.QuerySession(
       enc.encode(query + "\0"),
       enc.encode(format + "\0"),
       enc.encode(this.path + "\0"),
     );
+    if (result == null) {
+      return "";
+    }
+    return new Deno.UnsafePointerView(result).getCString();
   }
 
   constructor(path: string = "") {