OSV-2020-1529 Use-of-uninitialized-value in CorrectPSDAlphaBlend

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13836 Crash type: Use-of-uninitialized-value Crash state: CorrectPSDAlphaBlend ReadPSDMergedImage ReadPSDImage...