### Godot version

4.1.1

### System information

linux

### Issue description

The `"%+f"` format adds a `+` sign in front of positive numbers. If you try to format `-0.0`, it breaks and displays both a `+` and a `-`.

### Steps to reproduce

```gdscript
@tool
extends EditorScript

func _run() -> void:
    print("%+f" % -0.0)
```

### Minimal reproduction project

see above
int l = keys[k].length();
			for (int j = 0; j < l; j++) {
				int read_pos = i + j;
				if (read_pos >= len) {
					found = false;
					break;
				}
				if (src[read_pos] != cmp[j]) {
					found = false;
					break;
				}
			}
			if (found) {
				break;
			}
		}
		if (found) {
			return i;
		}
	}
	return -1;
}
int ::findn(const  &p_str, int p_from) const {
	if (p_from < 0) {
		return -1;
	}
	int src_len = p_str.length();
	if (src_len == 0 || length() == 0) {
		return -1; // 
	}