repl: Don't run empty code submission (#14598)

Closes #14565.

Release Notes:

- N/A

crates/repl/src/session.rs

@@ -284,6 +284,10 @@ impl Session {
             return;
         };
 
+        if code.is_empty() {
+            return;
+        }
+
         let execute_request = ExecuteRequest {
             code: code.to_string(),
             ..ExecuteRequest::default()