fix: revert scope util to omit empty-string scope values

Author: jankapunkt

lib/utils/scope-util.js

@@ -1,25 +1,16 @@
 const isFormat = require('@node-oauth/formats');
 const InvalidScopeError = require('../errors/invalid-scope-error');
-const toArray = s => Array.isArray(s) ? s : s.split(' ');
 
 module.exports = {
   parseScope: function (requestedScope) {
-    if (typeof requestedScope === 'undefined' || requestedScope === null) {
-      return undefined;
-    }
-
-    const internalScope = toArray(requestedScope);
-
-    if (internalScope.length === 0) {
+    if (!isFormat.nqschar(requestedScope)) {
       throw new InvalidScopeError('Invalid parameter: `scope`');
     }
 
-    internalScope.forEach(value => {
-      if (!isFormat.nqschar(value)) {
-        throw new InvalidScopeError('Invalid parameter: `scope`');
-      }
-    });
+    if (requestedScope == null) {
+      return undefined;
+    }
 
-    return internalScope;
+    return Array.isArray(requestedScope) ? requestedScope : requestedScope.split(' ');
   }
 };