Return false if the zip entry could not be located

Previously the function did not check whether the return value of `ZipArchive::locateName`
was `false`. And when it was, it was passed straight into `ZipArchive::getFromIndex`,
which casts it to an integer, resulting in it incorrectly retrieving the entry at index `0`.

Fixes #262
Closes #268

CHANGELOG.md

@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Control characters in cell values are automatically escaped - [#212](https://github.com/PHPOffice/PhpSpreadsheet/issues/212)
 - Prevent color changing when copy/pasting xls files written by PhpSpreadsheet to another file - @al-lala [#218](https://github.com/PHPOffice/PhpSpreadsheet/issues/218)
 - Add cell reference automatic when there is no cell reference('r' attribute) in Xlsx file. - @GreatHumorist [#225](https://github.com/PHPOffice/PhpSpreadsheet/pull/225) Refer to [issue#201](https://github.com/PHPOffice/PhpSpreadsheet/issues/201)
+- `Reader\Xlsx::getFromZipArchive()` function return false if the zip entry could not be located. - @anton-harvey [#268](https://github.com/PHPOffice/PhpSpreadsheet/pull/268)
 
 ### BREAKING CHANGE
 

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -308,13 +308,9 @@ class Xlsx extends BaseReader
         //    so we need to load case-insensitively from the zip file
 
         // Apache POI fixes
-        $contents = $archive->getFromIndex(
-            $archive->locateName($fileName, ZipArchive::FL_NOCASE)
-        );
+        $contents = $archive->getFromName($fileName, 0, ZipArchive::FL_NOCASE);
         if ($contents === false) {
-            $contents = $archive->getFromIndex(
-                $archive->locateName(substr($fileName, 1), ZipArchive::FL_NOCASE)
-            );
+            $contents = $archive->getFromName(substr($fileName, 1), 0, ZipArchive::FL_NOCASE);
         }
 
         return $contents;