Errors spewed in the console on switching the platform.

Steps To reproduce:

1. Download the project from : https://oc.unity3d.com/index.php/s/KCXAozid6yuh5DX
2. File > Build Settings > Switch to a different platform.

Observed Result:
1. "Channel or buffer mismatch in DSPGraph.ReadMix, re-init the DSPGraph with matching speaker and buffer size configurations" error is spewed in the console on switching to a different platform.

2. On Running any scene following error appears in the console: Trying to create a material from string - this is no longer supported.
UnityEngine.Material:.ctor(String)
_Visualizer:CreateLineMaterial() (at Assets/Common/_Visualizer.cs:51)
_Visualizer:OnPostRender() (at Assets/Common/_Visualizer.cs:11)

Reproducible On: 2019.1.0a9, 2019.1.0a2

Not Reproducible On: 2019.1.0a1, 2018.3.0b10

Environment: Occurs only on mac