### 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)

if (argument->is_constant) {
							if (argument->reduced_value.get_type() != Variant::INT && argument->reduced_value.get_type() != Variant::FLOAT) {
								can_reduce = false;
								push_error(vformat(R"*(Invalid argument for "range()" call. Argument %d should be int or float but "%s" was given.)*", i + 1, Variant::get_type_name(argument->reduced_value.get_type())), argument);
							}
							if (can_reduce) {
								args.write[i] = argument->reduced_value;
							}
						} else {
							can_reduce = false;
							GDScriptParser::DataType argument_type = argument->get_datatype();
							if (argument_type.is_variant() || !argument_type.is_hard_type()) {
								mark_node_unsafe(argument);
							}
							if (!argument_type.is_variant() && (argument_type.builtin_type != Variant::INT && argument_type.builtin_type != Variant::FLOAT)) {
								if (!argument_type.is_hard_type()) {
									downgrade_node_type_source(argument);
								} else {
									push_error(vformat(R"*(Invalid argument for "range()" call. Argument %d should be int or float but "%s" was given.)*", i + 1, argument_type.to_string()), argument);
								}
							}
						}
					}
					Variant reduced;
					if (can_reduce) {
						switch (args.size()) {
							case 1:
								reduced = (int32_t)args[0];
								break;
							case 2: