In the beginning of eclipse (movie), why does Bella say ' But if I had to preish twice ' ?

The Robert Frost poem goes

Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I now enought of hate
To say that for destruction ice
Is also great
And would suffice.


But when Bella quotes the poem in the meadow, she says

...
But if I had to perish twice
...

Why does she say ' I ' instead of ' it ' ?
Is it a mistake they didn't recognize or is it on purpose?