Issue 1:
Bug report

https://github.com/crazyair/webpack-demo

What is the current behavior?

➜ webpack-demo git:(master) ✗ yarn build
yarn run v1.22.5
warning package.json: No license field
$ webpack --progress --mode production --profile
assets by status 10.3 KiB [cached] 3 assets
runtime modules 5.29 KiB 7 modules
built modules 63 bytes [built]
./src/index.js 21 bytes [built] [code generated]
48 ms (resolving: 35 ms, restoring: 0 ms, integration: 0 ms, building: 13 ms, storing: 0 ms, additional resolving: 16 ms)
container entry 42 bytes [built] [code generated]
3 ms (resolving: 0 ms, restoring: 0 ms, integration: 0 ms, building: 2 ms, storing: 1 ms)

ERROR in demo.js from Terser
Unexpected token: operator (-) [demo.js:1,11]
at js_error (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:546:11)
at croak (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1264:9)
at token_error (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1272:9)
at unexpected (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1278:9)
at semicolon (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1309:56)
at statement (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1497:17)
at _embed_tokens_wrapper (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:1322:26)
at parse_toplevel (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:3439:23)
at parse (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:3451:7)
at minify (/Users/crazyair/Code/webpack-demo/node_modules/terser/dist/bundle.min.js:26237:38)

webpack 5.11.1 compiled with 1 error in 347 ms
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

If the current behavior is a bug, please provide the steps to reproduce.

yarn
yarn build

What is the expected behavior?

Other relevant information:

webpack version: latest

Node.js version: latest

Operating System: mac

Additional tools:

Issue 2:
Is webpack expected to work with 6.1.0? The ">=0.6" in engines.node suggests so, but the output I get from git clone, git checkout v1.13.0, npm install, npm test is:

3887 passing (2m)
19 pending
6 failing

1) ConfigTestCases extract-text issue-14 should compile:
Error: Cannot find module 'webpack/lib/ConcatSource'
at require (internal/module.js:20:19)
at require (internal/module.js:20:19)
at Object.<anonymous> (test/configCases/extract-text/issue-14/webpack.config.js:1:73)
at require (internal/module.js:20:19)
at Context.<anonymous> (test/ConfigTestCases.test.js:29:20)

2) Examples should compile code-splitted-css-bundle:
Error: Cannot find module 'webpack/lib/ConcatSource'
at require (internal/module.js:20:19)
at require (internal/module.js:20:19)
at Object.<anonymous> (examples/code-splitted-css-bundle/webpack.config.js:1:87)
at require (internal/module.js:20:19)
at Context.<anonymous> (test/Examples.test.js:20:15)

3) Examples should compile css-bundle:
Error: Cannot find module 'webpack/lib/ConcatSource'
at require (internal/module.js:20:19)
at require (internal/module.js:20:19)
at Object.<anonymous> (examples/css-bundle/webpack.config.js:1:87)
at require (internal/module.js:20:19)
at Context.<anonymous> (test/Examples.test.js:20:15)

4) Examples should compile i18n:
Error: Cannot find module 'webpack/lib/dependencies/ConstDependency'
at require (internal/module.js:20:19)
at require (internal/module.js:20:19)
at Object.<anonymous> (examples/i18n/webpack.config.js:2:18)
at require (internal/module.js:20:19)
at Context.<anonymous> (test/Examples.test.js:20:15)

5) Examples should compile multiple-entry-points-commons-chunk-css-bundle:
Error: Cannot find module 'webpack/lib/ConcatSource'
at require (internal/module.js:20:19)
at require (internal/module.js:20:19)
at Object.<anonymous> (examples/multiple-entry-points-commons-chunk-css-bundle/webpack.config.js:3:25)
at require (internal/module.js:20:19)
at Context.<anonymous> (test/Examples.test.js:20:15)

6) Examples should compile web-worker:
Error: done() invoked with non-Error: Cannot find module 'webpack/lib/webworker/WebWorkerTemplatePlugin'
@ (webpack)/examples/web-worker/example.js 1:13-39
at test/Examples.test.js:42:13
at Compiler.<anonymous> (lib/Compiler.js:194:14)
at Compiler.emitRecords (lib/Compiler.js:282:37)
at Compiler.<anonymous> (lib/Compiler.js:187:11)
at lib/Compiler.js:275:11
at Compiler.afterEmit (lib/Compiler.js:272:8)
at Compiler.<anonymous> (lib/Compiler.js:267:14)
at FSReqWrap.oncomplete (fs.js:117:15)

All the errors are missing module error, so I wonder if there's an additional step required to run tests locally.