Fix crash when opening a ZIP data pack

Co-authored-by: bruvzg <[email protected]>
(cherry picked from commit 0b65342fd2daddb91dcbcf84dff130856bde96df)

core/io/file_access_zip.h

@@ -84,8 +84,7 @@ public:
 };
 
 class FileAccessZip : public FileAccess {
-
-	unzFile zfile;
+	unzFile zfile = nullptr;
 	unz_file_info64 file_info;
 
 	mutable bool at_eof;