vm: simplify Script constructor options validation

This commit combines two related if statements into an
if-else statement.

PR-URL: #25054
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/vm.js

@@ -44,8 +44,7 @@ class Script extends ContextifyScript {
     code = `${code}`;
     if (typeof options === 'string') {
       options = { filename: options };
-    }
-    if (typeof options !== 'object' || options === null) {
+    } else if (typeof options !== 'object' || options === null) {
       throw new ERR_INVALID_ARG_TYPE('options', 'Object', options);
     }