Description:
------------
When try to `serialize` a class, `serialize` will try to get all properties of the class by `zend_get_properties_for`. Then it will get the count of the properties by `zend_array_count` without checking nullptr. 

`com` and `com_safearray_proxy` will always returns NULL in `com_properties_get` so it will crash on `zend_array_count`.

Affect code
------------------------
ext/standard/var.c

static void php_var_serialize_intern(smart_str *buf, zval *struc, php_serialize_data_t var_hash) /* {{{ */
[...]
incomplete_class = php_var_serialize_class_name(buf, struc);
myht = zend_get_properties_for(struc, ZEND_PROP_PURPOSE_SERIALIZE);
> i = zend_array_count(myht); // Crash here because myht == NULL
if (i > 0 && incomplete_class) {
  --i;
}


ext/com_dotnet/com_handlers.c

static HashTable *com_properties_get(zval *object)
{
	/* TODO: use type-info to get all the names and values ?
	 * DANGER: if we do that, there is a strong possibility for
	 * infinite recursion when the hash is displayed via var_dump().
	 * Perhaps it is best to leave it un-implemented.
	 */
	return NULL;
}



Test script:
---------------
<?php
$a = new COM("WScript.Shell");
serialize($a);

Expected result:
----------------
Nothing happened

Actual result:
--------------
Crash