### Godot version

v4.0.2.stable.custom_build (nixpkgs version)

### System information

NixOS

### Issue description

The [docs](https://docs.godotengine.org/en/latest/tutorials/scripting/gdscript/gdscript_basics.html#variables) seem to specify that uninitialized variables are null (as noted in this comment on the related issue: https://github.com/godotengine/godot/issues/56223#issuecomment-1175794500):
`var a # Data type is 'null' by default.`

This isn't always the case inside branches within loops. Instead, the variables can take on values from other branches.

### Related
- https://github.com/godotengine/godot/issues/56223

### Steps to reproduce

```
@tool
extends EditorScript

func _run():
	for i in 5:
		if i % 2:
			var j = i
			print("i = %s, j = %s" % [i, j])
		else:
			var k
			print("i = %s, k = %s" % [i, k])
```

Running this prints:
```
i = 0, k = <null>
i = 1, j = 1
i = 2, k = 1
i = 3, j = 3
i = 4, k = 3
```

This version also gives the exact same result:
```
@tool
extends EditorScript

func _run():
	for i in 5:
		match i % 2:
			1:
				var j = i
				print("i = %s, j = %s" % [i, j])
			0:
				var k
				print("i = %s, k = %s" % [i, k])
```

In addition, behavior similar to that described in https://github.com/godotengine/godot/issues/56223#issuecomment-1000996579 can still be reproduced as follows:
```
@tool
extends EditorScript

func _run():
	for i in 3:
		if i % 2:
			for j in range(1, 6, 3):
				pass
			print("i = %s" % i)
		else:
			var k
			var l
			var m
			print("i = %s, k = %s, l = %s, m = %s" % [i, k, l, m])
```
Which prints:
```
i = 0, k = <null>, l = <null>, m = <null>
i = 1
i = 2, k = 4, l = 7, m = (1, 6, 3)
```

### Minimal reproduction project

N/A
permission_args++;
				rpc_config["rpc_mode"] = MultiplayerAPI::RPC_MODE_ANY_PEER;
			} else if (arg == "authority") {
				permission_args++;
				rpc_config["rpc_mode"] = MultiplayerAPI::RPC_MODE_AUTHORITY;
			} else if (arg == "reliable") {
				transfer_mode_args++;
				rpc_config["transfer_mode"] = MultiplayerPeer::TRANSFER_MODE_RELIABLE;
			} else if (arg == "unreliable") {
				transfer_mode_args++;
				rpc_config["transfer_mode"] = MultiplayerPeer::TRANSFER_MODE_UNRELIABLE;
			} else if (arg == "unreliable_ordered") {
				transfer_mode_args++;
				rpc_config["transfer_mode"] = MultiplayerPeer::TRANSFER_MODE_UNRELIABLE_ORDERED;
			} else {
				push_error(R"(Invalid RPC argument. Must be one of: "call_local"/"call_remote" (local calls), "any_peer"/"authority" (permission), "reliable"/"unreliable"/"unreliable_ordered" (transfer mode).)", p_annotation);
			}
		}
		if (locality_args > 1) {
			push_error(R"(Invalid RPC config. The locality ("call_local"/"call_remote") must be specified no more than once.)", p_annotation);
		} else if (permission_args > 1) {
			push_error(R"(Invalid RPC config. The permission ("any_peer"/"authority") must be specified no more than once.)", p_annotation);
		} else if (transfer_mode_args > 1) {
			push_error(R"(Invalid RPC config. The transfer mode ("reliable"/"unreliable"/"unreliable_ordered") must be specified no more than once.)", p_annotation);
		}
	}
	function->rpc_config = rpc_config;
	return true;
}
bool GDScriptParser::static_unload_annotation(const AnnotationNode *p_annotation, Node *p_target) {