tests: Fill fuzzing coverage gaps for functions in consensus/validation.h

src/test/fuzz/block.cpp

@@ -38,12 +38,17 @@ void test_one_input(const std::vector<uint8_t>& buffer)
     const Consensus::Params& consensus_params = Params().GetConsensus();
     BlockValidationState validation_state_pow_and_merkle;
     const bool valid_incl_pow_and_merkle = CheckBlock(block, validation_state_pow_and_merkle, consensus_params, /* fCheckPOW= */ true, /* fCheckMerkleRoot= */ true);
+    assert(validation_state_pow_and_merkle.IsValid() || validation_state_pow_and_merkle.IsInvalid() || validation_state_pow_and_merkle.IsError());
+    (void)validation_state_pow_and_merkle.Error("");
     BlockValidationState validation_state_pow;
     const bool valid_incl_pow = CheckBlock(block, validation_state_pow, consensus_params, /* fCheckPOW= */ true, /* fCheckMerkleRoot= */ false);
+    assert(validation_state_pow.IsValid() || validation_state_pow.IsInvalid() || validation_state_pow.IsError());
     BlockValidationState validation_state_merkle;
     const bool valid_incl_merkle = CheckBlock(block, validation_state_merkle, consensus_params, /* fCheckPOW= */ false, /* fCheckMerkleRoot= */ true);
+    assert(validation_state_merkle.IsValid() || validation_state_merkle.IsInvalid() || validation_state_merkle.IsError());
     BlockValidationState validation_state_none;
     const bool valid_incl_none = CheckBlock(block, validation_state_none, consensus_params, /* fCheckPOW= */ false, /* fCheckMerkleRoot= */ false);
+    assert(validation_state_none.IsValid() || validation_state_none.IsInvalid() || validation_state_none.IsError());
     if (valid_incl_pow_and_merkle) {
         assert(valid_incl_pow && valid_incl_merkle && valid_incl_none);
     } else if (valid_incl_merkle || valid_incl_pow) {