Unify error handling of bad dictionary elements

As is, we have separate error handling and reporting for empty strings
and strings containing NUL bytes.  For simpler error handling we merge
both cases; while that is slightly worse regarding the error reporting,
it shouldn't matter in practice, since users need to check the validity
of the dictionary upfront anyway.

Author: cmb69

ext/zlib/tests/gh16326.phpt

@@ -21,6 +21,6 @@ try {
 }
 ?>
 --EXPECT--
-deflate_init(): Argument #2 ($options) must not contain empty strings
-deflate_init(): Argument #2 ($options) must not contain strings with null bytes
+deflate_init(): Argument #2 ($options) must not contain empty strings or strings with NUL bytes
+deflate_init(): Argument #2 ($options) must not contain empty strings or strings with NUL bytes
 Object of class stdClass could not be converted to string

ext/zlib/zlib.c

@@ -808,24 +808,15 @@ static bool zlib_create_dictionary_string(HashTable *options, char **dict, size_
 					zend_string **end, **ptr = strings - 1;
 
 					ZEND_HASH_FOREACH_VAL(dictionary, cur) {
-						*++ptr = zval_get_string(cur);
-						ZEND_ASSERT(*ptr);
-						if (ZSTR_LEN(*ptr) == 0 || EG(exception)) {
+						*++ptr = zval_try_get_string(cur);
+						if (*ptr == NULL || ZSTR_LEN(*ptr) == 0 || zend_str_has_nul_byte(*ptr)) {
 							do {
-								zend_string_release(*ptr);
+								if (*ptr != NULL) {
+									zend_string_release(*ptr);
+								}
 							} while (--ptr >= strings);
 							efree(strings);
-							if (!EG(exception)) {
-								zend_argument_value_error(2, "must not contain empty strings");
-							}
-							return 0;
-						}
-						if (zend_str_has_nul_byte(*ptr)) {
-							do {
-								zend_string_release(*ptr);
-							} while (--ptr >= strings);
-							efree(strings);
-							zend_argument_value_error(2, "must not contain strings with null bytes");
+							zend_argument_value_error(2, "must not contain empty strings or strings with NUL bytes");
 							return 0;
 						}