Her paragraph (p 134 in Bookworm is):
On her first visit, Lucy meets a talking lion called Aslan who fills her heart with love and she promises that she will return to help him. But her brothers and sister do not believe her (though Edmund is lying.....)and she almost has to go on without them. At the last minute Aslan becomes visible to them.....'
But the children all meet Aslan together (apart from Edmund who's buggered off in search of that Turkish Delight). So Lucy doesn't promise to come back and help him because they are already there. Yes, her siblings don't believe her, but that's about Narnia in general (because she says Edmund has also been and he's all like, what no, I never).
In fact, Peter is the first to approach Aslan, not Lucy. I dunno, I think these are all pretty big plot points to get wrong.
It's interesting actually in the Narnia section, Mangan is making the point that although the books 'sneak in the God stuff', not to worry because 'no child has or will be converted to Christianity through reading about Cair Paravel...fauns and all the rest. If they notice at all '
and yet her remembered reading focuses not on the iconic scene where Lucy meets a faun, but on the rather more overarching image of Aslan filling Lucy's heart with love, which is Lewis's most literal Christian message.