repl: remove unused variable from try catch

Catch statement defines err variable that is never used, so it
is safe to remove that.

Author: mmisiarek

lib/internal/repl/await.js

@@ -69,7 +69,7 @@ function processTopLevelAwait(src) {
   let root;
   try {
     root = acorn.parse(wrapped, { ecmaVersion: 10 });
-  } catch (err) {
+  } catch {
     return null;
   }
   const body = root.body[0].expression.callee.body;