### Godot version

Beta 17, master

### System information

Windows 11

### Issue description

Godot gets a hard crash while attempting to code-complete for member `const` of a class.

### Steps to reproduce

```GDScript
enum E { V1 }

const e := E
```

And then type a `.` after the last `E`, which triggers code hints/auto-completion for subscripts based on `E` and causes a hard crash.

Does not happen for `var e := E.V1`.

### Minimal reproduction project

See above.
ERR_FAIL_COND_MSG(p_node == nullptr, "Trying to resolve type of a null node.");
	switch (p_node->type) {
		case GDScriptParser::Node::NONE:
			break; 
		case GDScriptParser::Node::CLASS:
			if (OK == resolve_class_inheritance(static_cast<GDScriptParser::ClassNode *>(p_node), true)) {
				resolve_class_interface(static_cast<GDScriptParser::ClassNode *>(p_node), true);
				resolve_class_body(static_cast<GDScriptParser::ClassNode *>(p_node), true);
			}
			break;
		case GDScriptParser::Node::CONSTANT:
			resolve_constant(static_cast<GDScriptParser::ConstantNode *>(p_node), true);
			break;
		case GDScriptParser::Node::FOR:
			resolve_for(static_cast<GDScriptParser::ForNode *>(p_node));
			break;
		case GDScriptParser::Node::IF:
			resolve_if(static_cast<GDScriptParser::IfNode *>(p_node));
			break;
		case GDScriptParser::Node::SUITE:
			resolve_suite(static_cast<GDScriptParser::SuiteNode *>(p_node));
			break;
		case GDScriptParser::Node::VARIABLE: