Update packages/react-native/src/index.tsx

Co-authored-by: Delisa <kattrali@users.noreply.github.com>
Signed-off-by: Fran Aguilera <fran@bitdrift.io>

Author: FranAguilera

packages/react-native/src/index.tsx

@@ -79,7 +79,7 @@ export function error(
   const combinedFields = error ? {
     ...fields,
     _error: error.name || 'Error',
-    _error_details: error.message || '',
+    _error_details: error.message || undefined,
   } : fields;
 
   return logInternal('error', message, combinedFields);