src/internal.c: fix -Wnull-dereference in LoadCertByIssuer().

Author: douzzer

src/internal.c

@@ -14705,7 +14705,10 @@ int LoadCertByIssuer(WOLFSSL_X509_STORE* store, X509_NAME* issuer, int type)
             if (idx >= 0) {
                 WOLFSSL_MSG("find hashed CRL in list");
                 ph = wolfSSL_sk_BY_DIR_HASH_value(entry->hashes, idx);
-                suffix = ph->last_suffix;
+                if (ph)
+                    suffix = ph->last_suffix;
+                else
+                    suffix = 0;
             } else {
                 ph = NULL;
                 suffix = 0;