[arborist] [refactor] build-ideal-tree: remove unnecessary Promise stuff

Author: ljharb

workspaces/arborist/lib/arborist/build-ideal-tree.js

@@ -176,7 +176,7 @@ module.exports = cls => class IdealTreeBuilder extends cls {
   // public method
   async buildIdealTree (options = {}) {
     if (this.idealTree) {
-      return Promise.resolve(this.idealTree)
+      return this.idealTree
     }
 
     // allow the user to set reify options on the ctor as well.
@@ -194,8 +194,7 @@ module.exports = cls => class IdealTreeBuilder extends cls {
     process.emit('time', 'idealTree')
 
     if (!options.add && !options.rm && !options.update && this[_global]) {
-      const er = new Error('global requires add, rm, or update option')
-      return Promise.reject(er)
+      throw new Error('global requires add, rm, or update option')
     }
 
     // first get the virtual tree, if possible.  If there's a lockfile, then