handling for ESM (type="module") packages

[thescientist13]

Related Issue

#67

Found this issue when using in https://github.com/ProjectEvergreen/eleventy-plugin-wcc

% npm run demo

> [email protected] demo
> npm run build -- --serve


> [email protected] build
> npm run clean && eleventy "--serve"


> [email protected] clean
> rimraf ./_site

[11ty] Eleventy CLI Fatal Error: (more in DEBUG output)
[11ty] 1. Error in your Eleventy config file '/Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/.eleventy.js'. (via EleventyConfigError)
[11ty] 2. Must use import to load ES Module: /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/dist/wcc.dist.js
[11ty] require() of ES modules is not supported.
[11ty] require() of /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/dist/wcc.dist.js from /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/src/index.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
[11ty] Instead rename wcc.dist.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/package.json. (via Error)
[11ty]
[11ty] Original error stack trace: Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/dist/wcc.dist.js
[11ty] require() of ES modules is not supported.
[11ty] require() of /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/dist/wcc.dist.js from /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/src/index.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules.
[11ty] Instead rename wcc.dist.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/node_modules/wc-compiler/package.json.
[11ty]
[11ty]     at Object.Module._extensions..js (internal/modules/cjs/loader.js:1085:13)
[11ty]     at Module.load (internal/modules/cjs/loader.js:933:32)
[11ty]     at Function.Module._load (internal/modules/cjs/loader.js:774:14)
[11ty]     at Module.require (internal/modules/cjs/loader.js:957:19)
[11ty]     at require (internal/modules/cjs/helpers.js:88:18)
[11ty]     at Object.<anonymous> (/Users/owenbuckley/Workspace/project-evergreen/repos/eleventy-plugin-wcc/src/index.js:1:28)
[11ty]     at Module._compile (internal/modules/cjs/loader.js:1068:30)
[11ty]     at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10)
[11ty]     at Module.load (internal/modules/cjs/loader.js:933:32)
[11ty]     at Function.Module._load (internal/modules/cjs/loader.js:774:14)

Summary of Changes

1. Specified file extension specifically as .cjs
2. Updated README.md and package.json accordingly