Fix XLSX reader when having a corrupt numeric cell data type (#1664)

* fix for read xlsx with somewhat corrupt cell data type

CHANGELOG.md

@@ -128,6 +128,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Reader/Gnumeric Failure with PHP8 [#1662](https://github.com/phpoffice/phpspreadsheet/pull/1662)
 - ReverseSort bug, exposed but not caused by PHP8 [#1660](https://github.com/phpoffice/phpspreadsheet/pull/1660)
 - Bug setting Superscript/Subscript to false [#1567](https://github.com/phpoffice/phpspreadsheet/pull/1567)
+- Fix XLSX reader when having a corrupt numeric cell data type [#1664](https://github.com/phpoffice/phpspreadsheet/pull/1664) 
 
 ## 1.14.1 - 2020-07-19
 
@@ -656,4 +657,4 @@ For a comprehensive list of all class changes, and a semi-automated migration pa
 
 ## Previous versions of PHPExcel
 
-The changelog for the project when it was called PHPExcel is [still available](./CHANGELOG.PHPExcel.md).
+The changelog for the project when it was called PHPExcel is [still available](./CHANGELOG.PHPExcel.md).

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheet\Reader;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
+use PhpOffice\PhpSpreadsheet\Cell\DataType;
 use PhpOffice\PhpSpreadsheet\Cell\Hyperlink;
 use PhpOffice\PhpSpreadsheet\DefinedName;
 use PhpOffice\PhpSpreadsheet\Reader\Security\XmlScanner;
@@ -735,6 +736,10 @@ class Xlsx extends BaseReader
                                             $cell = $docSheet->getCell($r);
                                             // Assign value
                                             if ($cellDataType != '') {
+                                                // it is possible, that datatype is numeric but with an empty string, which result in an error
+                                                if ($cellDataType === DataType::TYPE_NUMERIC && $value === '') {
+                                                    $cellDataType = DataType::TYPE_STRING;
+                                                }
                                                 $cell->setValueExplicit($value, $cellDataType);
                                             } else {
                                                 $cell->setValue($value);