Check the block verification status of LDB-Block 0

It reads the Bitcoin Core LevelDB index (block/index) and uses the Blockstatus flag to determine if the block is valid and part of the active chain.

Currently using the following checks:

if ((BlockStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_CHAIN)

This seems to work for most blocks, but fails at block 0. 11.
As a result, the condition is evaluated error.

I think this is because block 0 is hardcoded and is probably handled differently by core.
So my question is:

1. Is this a reasonable proxy that assumes that the block is fully validated based solely on LevelDB metadata? Or is this check essentially unreliable for that purpose?
2. How does Bitcoin Core handle block status internally for block 0?
3. You must skip block 0 and apply this check only to blocks
   height > 0?