Cannot read properties of undefined (reading 'registerV2Addon')

[gossi]

I'm hunting a NPE for quite some time now - might be related to #1108

Cannot read properties of undefined (reading 'registerV2Addon')

I may have found a fix, but cannot be sure about this 100% yet - but enough to share here already.

The Situation

I'm upgrading hokulea to addons-v2. And with these addons v2 I see the error message above. Here is the monorepo and the dependency tree of relevant addons:

@hokulea/ember-actions-test-app
|- @hokulea/ember-actions
   |- ember-modifier
   `- @hokulea/ember-foundation
      `- ember-modifer

These are the noticable v2 addons, that will go through @embroider/addon-shim.

The Problem

Starting ember serve in @hokulea/ember-actions-test-app shows the error, that happens when an addon v2 depends on an addon v2 depends on an addon v2 - Two levels is the "threshold" here.

Reason for this in this line:

embroider/packages/addon-shim/src/index.ts

Line 77 in aa97453

(this.parent as EAI2Instance).registerV2Addon(this.name, directory);

which calls this method:

embroider/packages/addon-shim/src/index.ts

Lines 161 to 163 in aa97453

	registerV2Addon(name: string, root: string): void {
	autoImportInstance!.registerV2Addon(name, root);
	},

Now autoImportInstance is set in the code block linked above. Here is the trace in prose:

1. this instance is only available to its direct children @hokulea/ember-actions (in the tree above).
2. That is @hokulea/ember-actions has the chance to register its direct v2 addons (ember-modifer + @hokulea/ember-foundation).
3. But at the addon instance of @hokulea/ember-foundation this autoImportInstance is undefined
4. @hokulea/ember-foundation throws the error above

Given autoImportInstance is a local variable not "deeply" available, which makes sense and the reason for two levels being the threshold

1. first level: instantiation
2. second level: use
3. third level+: undefined 💣

The Suggested Fix

The fix is mentioned in the comment:

embroider/packages/addon-shim/src/index.ts

Lines 75 to 76 in aa97453

	// if we're being used by a v2 addon, it also has this shim and will
	// forward our registration onward to ember-auto-import

but not applied, it is not thrown "higher and higher". The fix would target registerV2Addon() method:

    registerV2Addon(name: string, root: string): void {
      if (autoImportInstance) {
        autoImportInstance.registerV2Addon(name, root);
      } else if (this.parent && this.parent.registerV2Addon) {
        this.parent.registerV2Addon(name, root);
      }
    },

Why I'm saying this is only a suggested fix: I'm not sure, if this piece of code is in the intention of the comment or if that means a different implementation (given I have basically no real knowledge about embroider).

What I can say, this makes my build passes this step - I have errors later on, so I cannot be sure as well.

This is ready enough for me for now to share. If my suggested fix is enough, then cool. If not a hint would be nice, so the next time I'm working on this, I can continue digging into it.

[ACsi]

I have had the same issue for some time now and have a similar solution. You can check it out here:

https://github.com/ACsi/embroider/tree/fix-addon-shim-registerv2addon-for-deeply-nested-addons