fix: link.target setter

There were guards in place to protect when setting a promise as a
target, which is not something the code actually does, which was
discovered after unpacking load-actual.

This removes those guards which are dangerous because either an
attribute is a promise or it's not.  Letting things access attributes as
non-promises that are sometimes promises is dangerous.

workspaces/arborist/lib/link.js

@@ -1,4 +1,3 @@
-const debug = require('./debug.js')
 const relpath = require('./relpath.js')
 const Node = require('./node.js')
 const _loadDeps = Symbol.for('Arborist.Node._loadDeps')
@@ -53,27 +52,6 @@ class Link extends Node {
       return
     }
 
-    if (current && current.then) {
-      debug(() => {
-        throw Object.assign(new Error('cannot set target while awaiting'), {
-          path: this.path,
-          realpath: this.realpath,
-        })
-      })
-    }
-
-    if (target && target.then) {
-      // can set to a promise during an async tree build operation
-      // wait until then to assign it.
-      this[_target] = target
-      // eslint-disable-next-line promise/always-return, promise/catch-or-return
-      target.then(node => {
-        this[_target] = null
-        this.target = node
-      })
-      return
-    }
-
     if (!target) {
       if (current && current.linksIn) {
         current.linksIn.delete(this)

workspaces/arborist/test/link.js

@@ -94,23 +94,6 @@ t.test('link.target setter', async t => {
   t.equal(oldTarget.linksIn.size, 0, 'old target still has no links')
   t.equal(newTarget.linksIn.size, 0, 'new target has no links in now')
 
-  const laterTarget = new Promise((res) =>
-    setTimeout(() => res(new Node({
-      path: '/node-later',
-      realpath: '/node-later',
-      pkg: { name: 'node-later', version: '1.2.3' },
-    }))))
-  link.target = laterTarget
-  t.equal(link.target, laterTarget, 'waiting for a new target to resolve')
-  t.throws(() => link.target = oldTarget, {
-    message: 'cannot set target while awaiting',
-    path: link.path,
-    realpath: link.realpath,
-  })
-  const node = await laterTarget
-  t.equal(link.target, node, 'target resolved and assigned')
-  t.equal(link.package, node.package, 'took on new targets package')
-  t.equal(node.linksIn.has(link), true, 'link in node.linksIn')
   link.target = null
   t.equal(link.target, null, 'target is now null')
   t.strictSame(link.package, {}, 'removed target, package is now empty')