Reproduction steps:
1. Create a new project
2. Install Entities 0.4.0-package.10 package

Expected result: No errors are thrown
Actual result: Package related errors are thrown

Reproducible with: 2020.1.0a11, 2020.1.0a16
Not reproducible with: 2018.4.15f1, 2019.2.17f1, 2019.3.0f4, 2020.1.0a9
Could not test with: 2017.4.36f1 (no Package Manager)

Reproducible with package versions: 0.4.0-preview.10
Not reproducible with package versions: 0.0.12-preview.24, 0.3.0-preview.4

Note: Errors are not thrown after downgrading to 0.3.0-preview.4

Errors:

Library\PackageCache\com.unity.entities@0.4.0-preview.10\Unity.Scenes.Editor\LiveLink\LiveLinkBuildPipeline.cs(257,61): error CS0117: 'ContentBuildInterface' does not contain a definition for 'GetPlayerObjectIdentifiersInSerializedFile'

Library\PackageCache\com.unity.entities@0.4.0-preview.10\Unity.Scenes.Editor\LiveLink\LiveLinkBuildPipeline.cs(323,37): error CS1579: foreach statement cannot operate on variables of type '?' because '?' does not contain a public instance definition for 'GetEnumerator'