Fixes: #62774

This PR adds graceful NULL checks for OpenSSL allocation function return values, replacing CHECK() assertions that would abort the process on allocation failure.

Changes

src/crypto/crypto_aes.cc — AES_Cipher()

Replaced CHECK(ctx) with:

if (!ctx) {
  return WebCryptoCipherStatus::FAILED;
}

This matches the pattern already used in AES_CTR_Cipher2() in the same file.

src/crypto/crypto_cipher.cc — CipherBase::CommonInit()

Replaced CHECK(ctx_) with:

if (!ctx_) {
  return ThrowCryptoError(env(),
                          mark_pop_error_on_return.peekError(),
                          "Failed to allocate cipher context");
}

This matches the error handling pattern used elsewhere in the same function.

Note on other locations from #62774

• AES_CTR_Cipher2() — Already has a proper if (!ctx) check (line 238)
• TLSSession::Initialize() — Already has a proper if (!ssl) check (line 794)
• ECKeyExportTraits::DoExport() — This function no longer exists in the current codebase; the EC key handling code has been refactored