Avoid uninitialized memory access
Avoid uninitialized memory access

As reported by https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=41430

MaartenBent/matio,tbeu/matio,MaartenBent/matio,tbeu/matio,MaartenBent/matio,tbeu/matio,MaartenBent/matio,tbeu/matio