The json is:
	{
	  "resourceType": "MedicationStatement",
	  "id": "example005",
	  "status": "entered-in-error",	  
	  "medicationCodeableConcept": {
		"coding": [
		  {
			"system": "http://snomed.info/sct",
			"code": "27658006",
			"display": "Amoxicillin (product)"
		  }
		]
	  },
	  "subject": {
		"reference": "Patient/4d5ed44d-ba1d-41b2-866e-5a9662278ae6",
		"display": "Donald Duck"
	  }
	}
	
   The error is: 
   Newtonsoft.Json.JsonWriterException: Token PropertyName in state Array would result in an invalid JSON object. Path 'medication.codeableconcept.coding'.
       at Newtonsoft.Json.JsonWriter.AutoComplete(JsonToken tokenBeingWritten)

   The failure also occurs just after writing system while the code is attempting to (prematurely)  "WriteEndObject:, but it also occurs without system and display (with just one contained field, the "code"). So there seems to be two issues: (a) the _isPolymorphic is causing the WriteEndObject to fire too soon instead of reading all contained fields, and (b) the WriteEndObject is confused (?) about the value to write for the Array state.

The json is:
	{
	  "resourceType": "MedicationStatement",
	  "id": "example005",
	  "status": "entered-in-error",	  
	  "medicationCodeableConcept": {
		"coding": [
		  {
			"system": "http://snomed.info/sct",
			"code": "27658006",
			"display": "Amoxicillin (product)"
		  }
		]
	  },
	  "subject": {
		"reference": "Patient/4d5ed44d-ba1d-41b2-866e-5a9662278ae6",
		"display": "Donald Duck"
	  }
	}

The error is thrown by: result.Add(_parser.Parse<T>(reader));
The error is: System.ArgumentException: Can not add Newtonsoft.Json.Linq.JValue to Newtonsoft.Json.Linq.JObject.