[Bug] Yielded undefined can be invoked as a component without error

### 🐞 Describe the Bug
This came up because I was losing my mind with a yielded component, only to find out that I had a typo. :upside_down_face:

### 🔬 Minimal Reproduction
Describe steps to reproduce. If possible, please, share a link with a minimal reproduction.

https://github.com/NullVoxPopuli/yield-undefined-repro

1. clone
2. ember s
3. click the button
4. I expect there to be an error, but there is none

### 😕 Actual Behavior

no error, but nothing is rendered

### 🤔 Expected Behavior

error, `No component manager found for undefined` or something like that

### 🌍 Environment

- Ember: - 3.25+
- Node.js/npm: - n/a
- OS: - n/a
- Browser: - n/a

### ➕ Additional Context

Prior to 3.25, I don't think this could have been an issue, because the previous _sole_ way to yield back components was with the `(component)` helper.