GHSA-G27H-8QHM-6PFF Excelize: Panic in cellInRange on a worksheet with an empty mergeCell ref

Summary A worksheet containing makes mergeCellsParser leave the cached rectangle empty, and cellInRange then indexes that empty slice without a length check. Every non-streaming cell API panics with index out of range 0 with length 0 on the first cell read after opening the file. Where it is...