@wordpress/scripts: code compiled with npm start works, and with npm run build does not, when doing an import by relative path from a different package

[leoloso]

Describe the bug
I have a plugin with multiple blocks (under folder blocks/) which access shared components. These shared components are located under a different folder within the same plugin (under folder packages/):

- blocks/
+    block1/
+    block2/
- packages/
+   components/

Every block and package has its own package.json file.

The blocks import the shared components through a relative path:

import { SelectCard } from '../../../packages/components/src';

This code worked well with @wordpress/scripts version 8.1.0.

However, after upgrading to version 10.0.0, it works when running npm start but not with npm run build.

There are no compilation errors, but when executing the code in the browser (when creating a new post on Gutenberg), the screen is all white, and in the console I get this error:

TypeError: e[t] is undefined

When clicking there:

var n=r[t]={i:t,l:!1,exports:{}};return e[t].call(n.exports,n,n.exports,a),n.l=!0,n.exports}a.m=e,

To reproduce
Steps to reproduce the behavior:

1. Reference a component not through the package name (eg: @wordpress/compose) but through the relative path within the project (eg: import { compose } from '../../packages/compose/src';
2. Run npm run build
3. Run Gutenberg (eg: a new post) in the browser

Expected behavior
I assume the relative path import across packages is not supported anymore, but this is not mentioned in the CHANGELOG, hence it's a guess.

If it is still supported, then code should work after running npm run build

If not supported anymore, then running npm start and npm run build should both fail (currently, npm start works well) and, ideally, the CHANGELOG should mention the steps needed to migrate the code

Editor version (please complete the following information):

• @wordpress/scripts versions 10.0.0, 11.0.0 and 12.0.0

[leoloso]

I have fixed the relative path import, and solved this issue. However, the different behavior between npm start and npm run build happens in other places too.

In another block, I display a GraphiQL client, with dependency:

"graphiql": "^0.17.5"

To import it:

import GraphiQL from 'graphiql';

It is used like this:

<GraphiQL
    fetcher={ graphQLFetcher }
    query={ query }
    variables={ variables }
    onEditQuery={ onEditQuery }
    onEditVariables={ onEditVariables }
    docExplorerOpen={ false }
/>

This code used to work well with @wordpress/scripts version 8.0.1. But after upgrading to version 10.0.0, npm start works, but npm run build throws several JS errors, including:

TypeError: Object(...) is not a function

Clicking on it, the code is this one:

Object(s.createElement)("path",{d:"M4.08 22.864l-1.1-.636L15.248.98l1.1.636z"})

[leoloso]

Closed in favor of #23607, which is more specific and provides better information