unexpected assertion error

[juzi5201314]

i am using the same code in the example to convert a bunch of pngs to dds, but when encountering an image of width: 170 height:156, an assertion failure occurs:

thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `26832`,
 right: `26528`', C:\Users\soeur\.cargo\registry\src\rsproxy.cn-8f6827c7555bfaf8\intel_tex-0.1.4\src\bc7.rs:32:5

this confuses me a lot, as if it only happens at certain image sizes