appendRemainingUnlimited

pub fn appendRemainingUnlimited(r: *Reader, gpa: Allocator, list: *ArrayList(u8)) UnlimitedAllocError!void {
    var a: std.Io.Writer.Allocating = .initOwnedSlice(gpa, list.allocatedSlice());
    a.writer.end = list.items.len;
    list.* = .empty;
    defer {
        list.* = .{
            .items = a.writer.buffer[0..a.writer.end],
            .capacity = a.writer.buffer.len,
            .pointer_stability = .{},
        };
    }
    _ = streamRemaining(r, &a.writer) catch |err| switch (err) {
        error.WriteFailed => return error.OutOfMemory,
        error.ReadFailed => |e| return e,
    };
}