fix(arborist): node.target can be null

[ljharb]

Followup to #7027. Fixes #6815.

Fixes this issue: https://github.com/ljharb/list-exports/actions/runs/7537180864/job/20515721981

[ljharb]

a node 16 test failed but since node 16 isn't supported anymore, i assume those tests can be dropped (and node 21 added)?

[lukekarrys]

I am still planning to add a failing test case for this in smoke-tests, but I do think this fix looks good.

[ljharb]

Thanks! I'm looking forward to it landing and being unblocked, and if there's anything concrete I can do to hurry it along I'd love pointers.

[dmnsgn]

I am getting a related Cannot destructure property 'package' of 'node.target' as it is null. but coming from another point in arborist's code than the above fix:

cli/workspaces/arborist/lib/arborist/rebuild.js

Line 270 in d04111d

const { package: pkg, hasInstallScript } = node.target

Using arborist@7.3.1 in node@v21.6.2 for a package with some dependencies as file: symlinks (with some being inter-dependent).

Stacktrace:

at [addToBuildSet] (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/rebuild.js:270:22)
at [buildQueues] (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/rebuild.js:210:41)
at [build] (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/rebuild.js:182:29)
at Arborist.rebuild (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/rebuild.js:100:25)
at async [reifyPackages] (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/reify.js:252:11)
at async Arborist.reify (/Users/myname/my-package/node_modules/@npmcli/arborist/lib/arborist/reify.js:171:5)

[lukekarrys]

@dmnsgn That looks like a different bug. Can you open a new issue about it including your package.json with the interdependent symlinks?

[dmnsgn]

@dmnsgn That looks like a different bug. Can you open a new issue about it including your package.json with the interdependent symlinks?

Sorry, I am having a hard time making a reduced case but a clue for solving the issue is removing a leftover package-lock.json in a workspace.
Let me just add that I was also getting Cannot read properties of undefined (reading 'target') when running npm query '*:missing' and the following stack (workspace.target being undefined at execWorkspaces):

npm info using npm@10.2.4
npm info using node@v21.6.2
// ...
npm verb stack TypeError: Cannot read properties of undefined (reading 'target')
npm verb stack     at Query.execWorkspaces (/usr/local/lib/node_modules/npm/lib/commands/query.js:104:33)
npm verb stack     at async module.exports (/usr/local/lib/node_modules/npm/lib/cli-entry.js:61:5)

Not sure it is worth opening an issue if I can't provide repro easily but maybe the above might help someone or "leftover package-lock" might ring a bell to someone who's worked on this.

[dmnsgn]

Another clue is: one of the workspace was dependent on another workspace but its dependency version was different.

Example: a is dependent on b@0.0.1, but b package.json version is 0.0.2.

.
+-- package.json
`-- packages
   +-- a@0.0.1
   |   `-- package.json (depends on b@0.0.1)
   `-- b@0.0.2
       `-- package.json

That solves it for me so I'll stop here and open another issue if I encounter these errors again. Hope that helps someone.