Uninitialized variable because we don't check return value

Warning 544870.5627882

Author: Andras Fekete

wolfcrypt/src/pkcs7.c

@@ -11489,8 +11489,13 @@ int wc_PKCS7_EncodeAuthEnvelopedData(PKCS7* pkcs7, byte* output,
             return MEMORY_E;
         }
 
-        FlattenAttributes(pkcs7, flatAuthAttribs, authAttribs,
+        ret = FlattenAttributes(pkcs7, flatAuthAttribs, authAttribs,
                           authAttribsCount);
+        if (ret != 0) {
+            wc_PKCS7_FreeEncodedRecipientSet(pkcs7);
+            XFREE(flatAuthAttribs, pkcs7->heap, DYNAMIC_TYPE_PKCS7);
+            return ret;
+        }
 
         authAttribsSetSz = SetImplicit(ASN_SET, 1, authAttribsSz,
                                        authAttribSet);