✅ Pull Request description:

This PR addresses the issue reported in the linked ticket, specifically the error:
Cannot traverse an already closed generator

The fix involves convertingTraversable input into an array usingiterator_to_array($data), in order to allow multiple traversals of generator-based inputs.

At first glance, it might seem that this approach significantly increases memory usage, since all generator values are stored in memory. However, this is not the case. In the current logic, the followingloop already forces all values from the generator into memory:

foreach ($dataas &$value) {$flattened = [];$this->flatten($value,$flattened,$keySeparator,'',$escapeFormulas);$value =$flattened;}

Therefore, materializing the generator withiterator_to_array()does not increase peak memory usage in any meaningful way.
As an example, here's the comparison of peak memory usage (measured withmemory_get_peak_usage) when processing an array of 1 million integers:

• With the fix: 90,044,272 bytes
• Without the fix: 89,936,680 bytes

The difference is negligible, confirming that the fix does not introduce a meaningful performance cost in terms of memory.