1. Create a new project
2. Import the 2D Animation package

Expected behavior: Editor runs properly and no errors are thrown
Actual behavior: Errors are thrown in the console

Reproducible with: 2019.2.0a1, 2019.2.0a14, 2019.3.0a1
Not reproducible with: 2018.3.14f1, 2018.4.0f1, 2019.1.1f1
Could not test with: 2017.4

Reproducible with package versions: 1.0.15, 1.0.16, 2.0.0, 2.1.0

Notes:
1. Could not test with 2017.4 due to the lack of a Package manager
2. Sometimes only one error is thrown:
Library\PackageCache\com.unity.collections@0.0.9-preview.16\Unity.Collections\UnsafeUtilityEx.cs(41,34): error CS0117: 'UnsafeUtility' does not contain a definition for 'IsUnmanaged'

3. Other times three errors are thrown:

Library\PackageCache\com.unity.2d.common@1.1.0-preview.2\Editor\ImagePacker\ImagePackerDebugEditor.cs(28,9): error CS0246: The type or namespace name 'SpriteRect' could not be found (are you missing a using directive or an assembly reference?)

Library\PackageCache\com.unity.2d.common@1.1.0-preview.2\Editor\InternalBridge\InternalEditorBridge.cs(28,23): error CS0246: The type or namespace name 'ISpriteEditorDataProvider' could not be found (are you missing a using directive or an assembly reference?)

Library\PackageCache\com.unity.2d.common@1.1.0-preview.2\Editor\InternalBridge\InternalEditorBridge.cs(59,50): error CS0246: The type or namespace name 'ISpriteEditor' could not be found (are you missing a using directive or an assembly reference?)