fix(tree): do not reveal nodes twice in sparse trie

[shekhirin]

Problem

Given the following targets for multiproof:

{
  0x9eb0b8d3a6a97287dcb36f92fa1d8a6d07d6cbd9e319b5a547e3302a7da66101: {
    0x61326283d49c3e01e81fa32d4d30080f9f2c5b41e7552947ee04b1ef14104967
  }
}

We get the following multiproof:

{
  0x9eb0b8d3a6a97287dcb36f92fa1d8a6d07d6cbd9e319b5a547e3302a7da66101: StorageMultiProof {
    root: 0x22135f62f626ed4496efa5c943668cfg64aefbd351f65fff82d13ae6c9d7bb16f,
    subtree: ProofNodes({
      Nibbles(""): 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,
      Nibbles("06"): 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,
      Nibbles("0601"): 0xeaa02016ab82ae691ddae1ee82cc57e1cb4288ef2aa9504c965532ad96d5de2f34c088870286a6966f7000,
    }),
  }
}

If we decode the node under the path 0601, we will get

["0x2016ab82ae691ddae1ee82cc57e1cb4288ef2aa9504c965532ad96d5de2f34c0","0x870286a6966f7000"]

which decodes to a leaf with a full path 0x6116ab82ae691ddae1ee82cc57e1cb4288ef2aa9504c965532ad96d5de2f34c0. As you can see, it's not a leaf that we requested in targets, so it's an exclusion proof.

The problem is that when we try to reveal that leaf in the sparse trie, and have the leaf 0x6116ab82ae691ddae1ee82cc57e1cb4288ef2aa9504c965532ad96d5de2f34c0 already revealed and turned into a branch node, the revealing of that leaf again will fail.

Solution

This PR makes a no-op all attempts to reveal a node that already exists and not a blinded node.

[rkrasiuk]

checks out

[shekhirin]

Testing

[shekhirin]

Fixes the issue