fix: check that there are whitelisted extensions before falling back to the first

Author: Oighty

programs/portal/src/error.rs

@@ -69,6 +69,8 @@ pub enum NTTError {
     InvalidReturnAccount,
     #[msg("Missing payer account")]
     MissingPayerAccount,
+    #[msg("No whitelisted extensions in swap global")]
+    NoWhitelistedExtensions,
 }
 
 impl From<ScalingError> for NTTError {

programs/portal/src/instructions/resolve_execute.rs

@@ -407,6 +407,12 @@ pub fn resolve_execute_vaa_v1<'a>(
     }
 
     // Find the extension program ID based on the destination mint
+    // Handle case where no extensions are whitelisted
+    if swap_global_data.whitelisted_extensions.is_empty() {
+        msg!("Cannot bridge to extension since none are whitelisted");
+        return err!(NTTError::NoWhitelistedExtensions);
+    }
+
     let ext_program = swap_global_data
         .whitelisted_extensions
         .iter()