core: use errors.Is for consensus errors check (#21095)

Author: robert-zaremba

core/blockchain.go

@@ -1706,13 +1706,13 @@ func (bc *BlockChain) insertChain(chain types.Blocks, verifySeals bool) (int, er
 	}
 	switch {
 	// First block is pruned, insert as sidechain and reorg only if TD grows enough
-	case err == consensus.ErrPrunedAncestor:
+	case errors.Is(err, consensus.ErrPrunedAncestor):
 		log.Debug("Pruned ancestor, inserting as sidechain", "number", block.Number(), "hash", block.Hash())
 		return bc.insertSideChain(block, it)
 
 	// First block is future, shove it (and all children) to the future queue (unknown ancestor)
-	case err == consensus.ErrFutureBlock || (err == consensus.ErrUnknownAncestor && bc.futureBlocks.Contains(it.first().ParentHash())):
-		for block != nil && (it.index == 0 || err == consensus.ErrUnknownAncestor) {
+	case errors.Is(err, consensus.ErrFutureBlock) || (errors.Is(err, consensus.ErrUnknownAncestor) && bc.futureBlocks.Contains(it.first().ParentHash())):
+		for block != nil && (it.index == 0 || errors.Is(err, consensus.ErrUnknownAncestor)) {
 			log.Debug("Future block, postponing import", "number", block.Number(), "hash", block.Hash())
 			if err := bc.addFutureBlock(block); err != nil {
 				return it.index, err
@@ -1895,13 +1895,13 @@ func (bc *BlockChain) insertChain(chain types.Blocks, verifySeals bool) (int, er
 		stats.report(chain, it.index, dirty)
 	}
 	// Any blocks remaining here? The only ones we care about are the future ones
-	if block != nil && err == consensus.ErrFutureBlock {
+	if block != nil && errors.Is(err, consensus.ErrFutureBlock) {
 		if err := bc.addFutureBlock(block); err != nil {
 			return it.index, err
 		}
 		block, err = it.next()
 
-		for ; block != nil && err == consensus.ErrUnknownAncestor; block, err = it.next() {
+		for ; block != nil && errors.Is(err, consensus.ErrUnknownAncestor); block, err = it.next() {
 			if err := bc.addFutureBlock(block); err != nil {
 				return it.index, err
 			}
@@ -1929,7 +1929,7 @@ func (bc *BlockChain) insertSideChain(block *types.Block, it *insertIterator) (i
 	// ones. Any other errors means that the block is invalid, and should not be written
 	// to disk.
 	err := consensus.ErrPrunedAncestor
-	for ; block != nil && (err == consensus.ErrPrunedAncestor); block, err = it.next() {
+	for ; block != nil && errors.Is(err, consensus.ErrPrunedAncestor); block, err = it.next() {
 		// Check the canonical state root for that number
 		if number := block.NumberU64(); current.NumberU64() >= number {
 			canonical := bc.GetBlockByNumber(number)