Careful with those variable length tuples

src/preserves.nim

@@ -882,6 +882,7 @@ proc fromPreserve*[T, E](v: var T; pr: Preserve[E]): bool =
         var i: int
         for name, field in fieldPairs(v):
           when v.dot(name).hasCustomPragma(preservesTupleTail):
+            if pr.len >= i:
               setLen(v.dot(name), pr.len - i)
               var j: int
               while result and i < pr.len: