Steps to reproduce:

1) Open Unity and create a new project with Lightweight RP (Preview) included
2) Switch platform to iOS/Android in the Build Settings
3) When compiling is finished, close the Editor
4) Open project again and you will see shader errors in the Console window

Expected result: No errors in the Console window after reopening a project which uses Lightweight RP (Preview) project
Actual result: Shader error shown in the Console

Reproduced with:
2018.1.0b11, 2018.1.0b12, 2018.1.0f1, 2018.2.0a9

Not reproduced with:
2018.1.0b10

Tested using :
MacBook Pro (15-inch 2017)
Mac OS High Sierra 10.13.4 (17E199)

Windows 10 machine reproduced this issue also

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Fixed in: 2018.3.0a1