### 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
for (const KeyValue<StringName, IdentifierNode *> &E : branch->patterns[0]->binds) {
			SuiteNode::Local local(E.value, current_function);
			local.type = SuiteNode::Local::PATTERN_BIND;
			suite->add_local(local);
		}
	}
	branch->block = parse_suite("match pattern block", suite);
	complete_extents(branch);
	return branch;
}
GDScriptParser::PatternNode *GDScriptParser::parse_match_pattern(PatternNode *p_root_pattern) {
	PatternNode *pattern = alloc_node<PatternNode>();
	reset_extents(pattern, current);
	switch (current.type) {
		case GDScriptTokenizer::Token::VAR: {
			
			advance();
			if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected bind name after "var".)")) {
				complete_extents(pattern);
				return nullptr;
			}
			pattern->pattern_type = PatternNode::PT_BIND;
			pattern->bind = parse_identifier();
			PatternNode *root_pattern = p_root_pattern == nullptr ? pattern : p_root_pattern;
			if (p_root_pattern != nullptr) {
				if (p_root_pattern->has_bind(pattern->bind->name)) {
					push_error(vformat(R"(Bind variable name "%s" was already used in this pattern.)", pattern->bind->name));
					complete_extents(pattern);
					return nullptr;
				}