fix linter issues

core/blockchain_test.go

@@ -2408,6 +2408,9 @@ func TestProcessingStateDiffs(t *testing.T) {
 
 	moreBlocks := makeBlockChain(blocks[len(blocks)-1], 1, engine, db, canonicalSeed)
 	_, err = blockchain.InsertChain(moreBlocks)
+	if err != nil {
+		t.Error(err)
+	}
 
 	//a root hash can be dereferenced when it's state diff and it's child's state diff have been processed
 	//(i.e. it has a count of 2 in stateDiffsProcessed)

statediff/testhelpers/mocks/api_test.go

@@ -166,6 +166,9 @@ func testHTTPAPI(t *testing.T) {
 		streamBlock: true,
 	}
 	payload, err := mockService.StateDiffAt(block1.Number().Uint64())
+	if err != nil {
+		t.Error(err)
+	}
 	expectedBlockRlp, _ := rlp.EncodeToBytes(block1)
 	if !bytes.Equal(payload.BlockRlp, expectedBlockRlp) {
 		t.Errorf("payload does not have expected block\r\actual block rlp: %v\r\nexpected block rlp: %v", payload.BlockRlp, expectedBlockRlp)