How to reproduce:
1. Open the "TextureStreamingBug.zip" project
2. Open the "Demo.unity" scene
3. Press Play
4. Press "Crash me" button

Actual result: Unity crashes.

Reproducible with: 2019.3.0a6, 2019.2.0b6, 2019.1.7f1, 2018.4.2f1, 2018.2.21f1, 2018.2.0b1.
Not reproducible with: 2018.2.0a8.

Notes:
Texture Streaming appeared in 2018.2.
Crash happens after failed assertion: "Assertion failed on expression: 'batch < desiredMipLevels.size()'".
The user claims that the crash happens when switching the quality level when the current frame's texture streaming job batch index is 1.

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fixed in 2019.3.0a8, 2019.2.0b8, 2019.1.10f1, 2018.4.4f1.