Fix `staticcheck` issues:
- S1028 use `fmt.Errorf` to construct formatted errors
- ST1017 yoda conditions
- ST1005 error message capitalization
- ST1006 avoid `self` as receiver name
- S1030 use `buf.String`
- S1011 avoid redundant loop when `append` suffices
- SA4006 unused value
- S1019 remove redundant capacity on `make` call
- SA2002 `t.Fatal` called outside of test
Exported error violates ST1012, which is ignored by this PR since rename may cause breaking changes.
Remove redundant parentheses wrapping, and use CamelCase naming while at it.
As pointed out by ishbir in issue 24, the applyKeyAndIV function was
incorrectly always using EVP_EncryptInit_ex(), even when the underlying
context being initialized was for a decryption.
This change causes it to select the right initializer based on the
"encrypt" field in the EVP_CIPHER_CTX. A test is also added which
verifies a fix.
Closes#24.
