Steps to Reproduce

1. Open attached xlsx in keikai 6
2. Go to cell I3
3. Type formula =ISNUMBER(A1:I1)
4. Go to cell J3
5. Type formula =ISNUMBER(A1:I1)

Current Result

I3: true
J3: #Value

Expected Result

Both #value or both true, or a different error on both to denote lack of support

Debug Information

Caused by
org.apache.poi.ss.formula.WorkbookEvaluator.dereferenceResult(ValueEval, int, int)
Trying to fit the result of the array formula (isNumber with an array as argument, should output an array of results, but not supported in Keikai), trying to create a result from a single cell (first cell of the input array).

attempts to use org.apache.poi.ss.formula.eval.OperandResolver.chooseSingleElementFromArea(AreaEval, int, int) to retrieve the cell, but is conditional on the formula holding cell (I3 or J3) being located in the same column span as the source cells (A1:I1)
If the cell is inside columns A to I, the first cell of the array is returned
If the cell is outside of the columns range, a #value error is returned

Workaround

No workaround, because the usage is not supported.
The purpose of this ticket is to have a consistent behavior (consistent fail) to avoid false positives