expiring-todo-comments doesn't work when linting stand-alone files

[garyking]

Related to #373. Ping @lubien.

I'm using the latest version of eslint-plugin-unicorn, and eslint v5.

I'm using the latest version of the VS Code editor, and the latest version of the vscode-eslint extension.

The extension allows to lint untitled files (after changing the untitled file's lang to JavaScript), and files that don't belong to a JS project with package.json. But an error is thrown with this rule, since it checks for a package.json, and an untitled file isn't even a file at all, and therefore also has no relevant package.json. And stand-alone files don't have package.json.

Error, whenever I open an untitled or stand-alone file in VSC:

[Info  - 4:23:17 PM] ESLint server stopped.
[Info  - 4:23:18 PM] ESLint server running in node v10.11.0
[Info  - 4:23:18 PM] ESLint server is running.
[Info  - 4:23:19 PM] ESLint library loaded from: /usr/local/lib/node_modules/eslint/lib/api.js
[Error - 4:23:21 PM] ESLint stack trace:
[Error - 4:23:21 PM] TypeError: Cannot read property 'package' of undefined
    at Object.<anonymous> (/usr/local/lib/node_modules/eslint-plugin-unicorn/rules/expiring-todo-comments.js:20:29)
    at Object.<anonymous> (/usr/local/lib/node_modules/eslint-plugin-unicorn/rules/expiring-todo-comments.js:499:3)
    at Module._compile (internal/modules/cjs/loader.js:693:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:704:10)
    at Module.load (internal/modules/cjs/loader.js:602:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:541:12)
    at Function.Module._load (internal/modules/cjs/loader.js:533:3)
    at Module.require (internal/modules/cjs/loader.js:640:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at module.exports (/usr/local/lib/node_modules/eslint-plugin-unicorn/node_modules/import-modules/index.js:41:21)

[lubien]

I can totally see this happening but I couldn't reproduce the untitled file scenario.

There is a .eslintrc with our plugin. Here's the output after changing it to JS:

[Info  - 7:57:17 PM] ESLint server stopped.
[Info  - 7:57:18 PM] ESLint server running in node v12.4.0
[Info  - 7:57:18 PM] ESLint server is running.
[Info  - 7:57:19 PM] ESLint library loaded from: /home/lubien/.nvm/versions/node/v10.16.0/lib/node_modules/eslint/lib/api.js
[Warn  - 7:57:19 PM] 
No ESLint configuration (e.g .eslintrc) found for file: Untitled-1

But I can reproduce it if I save the file, for that I think I have a fix.