[Bug] String injection with `instantiate: false` no longer works on ember 3.27.0

🐞 Describe the Bug

Injecting a string via dependency injection raise an error.

🔬 Minimal Reproduction

Minimal reproduction on fresh app : https://github.com/romgere/test-ember-string-injection

• Currently on ember 3.26 : working
• Update to ember-source@3.27.0 : breaking

To sum-up Try to inject a string into a service with an initializer :

// initializer.js
export function initialize(application) {
  application.register('config:a-string', 'My great injected string', {
    instantiate: false,
  });

  application.inject(
    'service:test-injection',
    'injectedString',
    'config:a-string'
  );
}

export default {
  initialize,
};

// service.js
import Service from '@ember/service';

export default class TestInjectionService extends Service {
  injectedString = null; // injected by initializer
}

😕 Actual Behavior

When trying to use the service property got the following error :

Uncaught TypeError: Cannot create property 'Symbol(INIT_FACTORY)' on string 'My great injected string'

🤔 Expected Behavior

The property is setted with injected string.

🌍 Environment

• Ember: 3.27.0
• Node.js/npm: v12.20.2 (npm v6.14.11)
• OS: ubuntu
• Browser: chrome

➕ Additional Context

Related to what is done in https://github.com/yapplabs/ember-modal-dialog, see https://github.com/yapplabs/ember-modal-dialog/issues/320.

[lifeart]

as workaround,

 application.register('config:a-string', { toString() => 'My great injected string' }, {
    instantiate: false,
  });

may work

[andsmedeiros]

Thanks @lifeart, this does the trick.