lint: add errchecks (#5316)

## Description

Work towards enabling errcheck

ref #5059

crypto/hash.go

@@ -6,6 +6,6 @@ import (
 
 func Sha256(bytes []byte) []byte {
 	hasher := sha256.New()
-	hasher.Write(bytes)
+	hasher.Write(bytes) //nolint:errcheck // ignore error
 	return hasher.Sum(nil)
 }

crypto/merkle/proof_value.go

@@ -80,13 +80,13 @@ func (op ValueOp) Run(args [][]byte) ([][]byte, error) {
 	}
 	value := args[0]
 	hasher := tmhash.New()
-	hasher.Write(value) // does not error
+	hasher.Write(value) //nolint: errcheck // does not error
 	vhash := hasher.Sum(nil)
 
 	bz := new(bytes.Buffer)
 	// Wrap <op.Key, vhash> to hash the KVPair.
-	encodeByteSlice(bz, op.key) // does not error
-	encodeByteSlice(bz, vhash)  // does not error
+	encodeByteSlice(bz, op.key) //nolint: errcheck // does not error
+	encodeByteSlice(bz, vhash)  //nolint: errcheck // does not error
 	kvhash := leafHash(bz.Bytes())
 
 	if !bytes.Equal(kvhash, op.Proof.LeafHash) {

crypto/xchacha20poly1305/xchachapoly_test.go

@@ -23,10 +23,22 @@ func TestRandom(t *testing.T) {
 		pl := mr.Intn(16384)
 		ad := make([]byte, al)
 		plaintext := make([]byte, pl)
-		cr.Read(key[:])
-		cr.Read(nonce[:])
-		cr.Read(ad)
-		cr.Read(plaintext)
+		_, err := cr.Read(key[:])
+		if err != nil {
+			t.Errorf("error on read: %w", err)
+		}
+		_, err = cr.Read(nonce[:])
+		if err != nil {
+			t.Errorf("error on read: %w", err)
+		}
+		_, err = cr.Read(ad)
+		if err != nil {
+			t.Errorf("error on read: %w", err)
+		}
+		_, err = cr.Read(plaintext)
+		if err != nil {
+			t.Errorf("error on read: %w", err)
+		}
 
 		aead, err := New(key[:])
 		if err != nil {