* fix: more robust handling of var declarations
- fixes#12807: state declared with var is now retrieved using a new `safe_get` function, which works like `get` but checks for undefined
- fixes#12900: ensure we're not creating another new scope for block statements of function declarations, which resulted in var declarations getting "swallowed" (because they were hoisted to the function declaration scope and never seen by our logic)
* simplify
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Co-authored-by: Rich Harris <rich.harris@vercel.com>