Problem

• Parsing of "a" generates AST that is not consistent with definition in types.ts
• Based on types.ts, "operation" property is NOT optional
• Parsing of "a" generates TagToken w/o "operation" property - example here

Proposed solution

• Fix types.ts or parser

Versions

• 3.5.0 - on https://npm.runkit.com/liqe
• 3.6.0 - with Angular 14.0.4

Generated AST

{
	"location": {
		"start": 0,
		"end": 1
	},
	"field": {
		"type": "ImplicitField"
	},
	"type": "Tag",
	"expression": {
		"location": {
			"start": 0,
			"end": 1
		},
		"type": "LiteralExpression",
		"quoted": false,
		"value": "a"
	}
}