Stack overflow in array:flatten for very large arrays

[bwrrp]

See the following playground example: https://xpath.playground.fontoxml.com/?state=H4sIACFKG2MAAzVMWwqDMBC8ynS%2FFARrP4PNHXqEtd1CIRpIV1FC7u4qOD%2FzYGYyjfEj5LqGFk4%2FHoL8yVEu1NA6BpO9UesP%2B5olbZZwSrwho%2BqgEY%2B7ocYN%2FRC49Sh4epwV9w2sKlNVw%2BbvOKmsep1Q2QEhXQJZewAAAA%3D%3D

Expected: sequence of the 20k items in the array Actual: stack overflow in both Chrome and Firefox

I wasn't able to determine exactly where the infinite recursion happens. The flattenItem function is recursive, but only along the structure of the array, which is flat in this case. The stack trace seen in the debugger implies the actual overflow happens in a repeating series of next() calls (note the repeating column numbers):

"RangeError: Maximum call stack size exceeded
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:444843)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:447687)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:444914)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:464694)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:444914)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:447687)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:444914)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:464694)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:444914)
    at Object.next (https://xpath.playground.fontoxml.com/static/js/1.7d5907a9.chunk.js:1:447687)"