### Godot version

v4.0.rc1.official [8843d9ad3]

### System information

Lubuntu

### Issue description

You can't use + or += to mutate typed arrays.

It seems to be not correctly getting the type information from the second operand.

An erudite poster on the discord puts it differently:
> it's more like operator + doesn't retain Array typing
> the syntax for Array Concatenation via operators, but the idea gets across i think


The error you see is:
```Trying to assign an array of type "Array" to a variable of type "Array[int]".```


### Steps to reproduce

```
	var Alice: Array[int] = [1,2,3]
	var Bob: Array[int] = [4,5,6]
	Alice += Bob
```
This will crash with the above error message.

### Minimal reproduction project

[plus_syntax_broken_demo_project.zip](https://github.com/godotengine/godot/files/10694514/plus_syntax_broken_demo_project.zip)

parser->push_warning(member.variable, GDScriptWarning::ONREADY_WITH_EXPORT);
				}
				if (member.variable->initializer) {
					
					
					if (!member.variable->is_static && !member.variable->onready && member.variable->initializer && (member.variable->initializer->type == GDScriptParser::Node::GET_NODE || member.variable->initializer->type == GDScriptParser::Node::CALL || member.variable->initializer->type == GDScriptParser::Node::CAST)) {
						GDScriptParser::Node *expr = member.variable->initializer;
						if (expr->type == GDScriptParser::Node::CAST) {
							expr = static_cast<GDScriptParser::CastNode *>(expr)->operand;
						}
						bool is_get_node = expr->type == GDScriptParser::Node::GET_NODE;
						bool is_using_shorthand = is_get_node;
						if (!is_get_node && expr->type == GDScriptParser::Node::CALL) {
							is_using_shorthand = false;
							GDScriptParser::CallNode *call = static_cast<GDScriptParser::CallNode *>(expr);
							if (call->function_name == SNAME("get_node")) {
								switch (call->get_callee_type()) {
									case GDScriptParser::Node::IDENTIFIER: {
										is_get_node = true;
									} break;
									case GDScriptParser::Node::SUBSCRIPT: {
										GDScriptParser::SubscriptNode *subscript = static_cast<GDScriptParser::SubscriptNode *>(call->callee);
										is_get_node = subscript->is_attribute && subscript->base->type == GDScriptParser::Node::SELF;
									} break;
									default:
										break;
								}
							}
						}
						if (is_get_node) {