fix: read XLS literal error cells as errors instead of booleans

[codeAnqiang-ma]

Purpose of the pull request

Closed: #1010

What's changed?

A .xls cell holding a literal error value — an error stored as the cell value rather than as a formula result, e.g. after "Paste Special → Values" — was read as a boolean, while the same content in .xlsx read correctly:

cell	POI usermodel	Fesod .xls before	Fesod .xlsx
#DIV/0!	ERROR	true	#DIV/0!
#N/A	ERROR	true	#N/A
#NULL!	ERROR	false	#NULL!

A BIFF BOOLERR record holds either a boolean or an error code (fError flag, exposed by POI as isBoolean()/isError()), but BoolErrRecordHandler called getBooleanValue() unconditionally — POI returns errorCode != 0 for error records, so non-zero codes became true and #NULL! (code 0) became false.

The handler now branches on isError() and emits a CellDataTypeEnum.ERROR cell carrying the error text, which the existing StringErrorConverter renders as the value XLSX already produces. That matches FormulaRecordHandler (XLS formula errors are already ERROR) and CellTagHandler (t="e" → error text); the boolean branch is unchanged. The text comes from ErrorEval.getText(...), as in POI's own DataFormatter.

BoolErrRecordHandlerTest writes that row to both formats and asserts they read back identically, in STRING and ACTUAL_DATA mode.

Test evidence: fails before the fix, passes after, no regressions

Before the fix (test present, BoolErrRecordHandler at main) — both cases fail:

[ERROR] BoolErrRecordHandlerTest.read_literalErrorCells_returnErrorText_inStringMode:68
        expected: <{0=true, 1=#DIV/0!, 2=#N/A, 3=#NULL!, 4=marker}>
         but was: <{0=true, 1=true,    2=true, 3=false,  4=marker}>
[ERROR] BoolErrRecordHandlerTest.read_literalErrorCells_returnErrorText_inActualDataMode:79
        expected: <#DIV/0!> but was: <true>
[ERROR] Tests run: 2, Failures: 2, Errors: 0, Skipped: 0

After the fix:

$ ./mvnw test -pl fesod-sheet -Dmaven.test.skip=false -Dtest=BoolErrRecordHandlerTest
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0

Full module suite and format check:

$ ./mvnw test -pl fesod-sheet -Dmaven.test.skip=false
[INFO] Tests run: 681, Failures: 0, Errors: 0, Skipped: 0     # 679 before, +2 new
[INFO] BUILD SUCCESS

$ ./mvnw spotless:check
[INFO] BUILD SUCCESS

Run on JDK 21 (Temurin 21.0.5). I did not run the other JDKs of the CI matrix (8/11/17/25) locally; the change uses no version-specific API.

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

_{Assisted-by: Cursor (Fable 5). I reproduced the behaviour locally and reviewed every line of this change and its test myself.}