Strict mode has seemingly no effect on partials

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- [x] Please don't open issues for security issues. Instead, file a report at https://www.npmjs.com/advisories/report?package=handlebars
- [x] Have a look at https://github.com/wycats/handlebars.js/blob/master/CONTRIBUTING.md
- [x] Read the FAQ at https://github.com/wycats/handlebars.js/blob/master/FAQ.md
- [ ] Use the jsfiddle-template at https://jsfiddle.net/4nbwjaqz/4/ to reproduce problems or bugs
(I put together an example on runkit before i realized you had a base fiddle, hopefully thats alright.

This will probably help you to get a solution faster.
For bugs, it would be great to have a PR with a failing test-case.

## The issue:
When using strict mode and passing a parameter into a partial, no error is thrown when that value is missing.

### Example
See this running example here: https://runkit.com/jemarjones/handlebars-strict-mode-partials
```
const Handlebars = require("handlebars");
Handlebars.registerPartial('myPartial', 'Hello {{name}}')
const template = Handlebars.compile('{{>myPartial name=name}}', {strict: true})
console.log(template({name: 'World'})) // 'Hello World'
// ^ Good, makes sense.

console.log(template({})) // 'Hello '
// ^ This should be throwing an error

const template2 = Handlebars.compile('{{name}}', {strict: true})
console.log(template2({})) // "name" not defined in [object Object]
// ^ Not the best error message, but it does work when the missing value is used in the base template at least.
```

Start with the minimal example using Handlebars.registerPartial and Handlebars.compile(..., {strict: true}), comparing the partial case with the base-template case. Reproduce the missing-value behavior, then add a failing test showing that strict mode should report the absent partial parameter while preserving the successful rendering case.

Written by the indexing model from the issue text.