Whenever in array mode, 
  a) operands are collected for an array function or 
  b) array function is evaluated, 
and an ErrorEval is encountered, an EvaluationException is thrown, and the whole result is set to ErrorEval. This doesn't correspond to Excel behavior, where calculations fall into separate "threads", so that an error in a "thread" doens't affect other ones.

Example:
A |   B   | C |   D   |   E   |   F   |
1 | #N/A! | 2 |     {=A1:C1*A1:C1}    |
=======================================
expected      |   1   | #N/A! |   4   |
actual        | #N/A! | #N/A! | #N/A! |

A testcase:

@Test
public void elementwiseEvaluation() {
    Workbook workbook = new XSSFWorkbook();
    Row row = workbook.createSheet().createRow(0);
    row.createCell(0).setCellValue(1);
    row.createCell(1).setCellErrorValue(FormulaError.NUM.getCode());
    row.createCell(2).setCellValue(2);
    row.getSheet().setArrayFormula("A1:C1*A1:C1", CellRangeAddress.valueOf("D1:F1"));

    workbook.getCreationHelper().createFormulaEvaluator().evaluateAll();

    assertEquals(CellType.NUMERIC, row.getCell(3).getCachedFormulaResultType());
    assertEquals(1, row.getCell(3).getNumericCellValue(), 0);

    assertEquals(CellType.ERROR, row.getCell(4).getCachedFormulaResultType());
    assertEquals(FormulaError.NUM.getCode(), row.getCell(4).getErrorCellValue());

    assertEquals(CellType.NUMERIC, row.getCell(5).getCachedFormulaResultType());
    assertEquals(4, row.getCell(5).getNumericCellValue(), 0);
}