`Error: null is not a ReactiveResource or Model known to WarpDrive` with schemas (legacy)

[mkszepp]

While moving from models to schemas we were running into this error:

Steps:

1. Clone https://github.com/mkszepp/warp-drive-null-reactive-resource-error
2. pnpm i & pnpm start
3. Go to http://localhost:4200/ and click on Grand Old Mansion or go directly to http://localhost:4200/1
4. Click on "delete" button
5. Error will thrown

This issue is only present with schemas, with models this issue will not happen.
If you rename the folder _models to models and disable in store.js the schema imports you can test the behavior with models, which is correct.

Notes:

• The issue will gone way, when you disable the <p>{{this.model.owner.name}}</p> in detail.gts.
• In our app we have a similar error with hasMany, maybe its related. (TypeError: can't access property "length", source is undefined`)
  
  Error is in this line:
  

  warp-drive/scripts/benchmark-push.js

  Line 12 in ec6ee6a

  const newLength = source.length;

  
  The fastPush was called from this function
  

  warp-drive/warp-drive-packages/core/src/reactive/-private/fields/many-array-manager.ts

  Lines 34 to 56 in ec6ee6a

  	_syncArray(array: ManyArray): void {
  	const method = this.editable ? 'getRelationship' : 'getRemoteRelationship';
  	// FIXME field needs to use sourceKey
  	const rawValue = this.store.cache[method](this.identifier, array.key) as CollectionRelationship;
  	if (rawValue.meta) {
  	array.meta = rawValue.meta;
  	}
  	if (rawValue.links) {
  	array.links = rawValue.links;
  	}
  	const currentState = array[Context].source;
  	// unlike in the normal RecordArray case, we don't need to divorce the reference
  	// because we don't need to worry about associate/disassociate since the graph
  	// takes care of that for us
  	if (currentState !== rawValue.data) {
  	currentState.length = 0;
  	fastPush(currentState, rawValue.data as ResourceKey[]);
  	}
  	}