Reproduction steps:

1. Open "ShaderTargetBroken.zip" project
2. Click on "ArrayShadeBroken" and see that there is an error "Undefined variable...(d3d9)"
3. Click on "ArrayShadeWorking" and see that there are no errors

Expected Result: No errors regarding DirectX 9 should appear as the graphics API is not included
Actual Result: DirectX 9 errors appear, because of using features not supported by it

Fixed from 2017.2. For a fix with earlier versions, use the workaround at the bottom.

Reproduced with: 2017.1.1p4, 5.6.3p4, 5.5.5f1
Did not reproduce on: 2017.3.0b3, 2017.2.0f2 (Unexpected identifier "Texture2DArray". Expected: ')')

Note:
If the error doesn't appear immediately, change something in the broken shader, save, go back to the editor, revert changes to script and come back to the Editor

Graphics API's are set to DirectX 11, Vulkan and Metal

The issue is worked around by using "#if SHADER_TARGET > 30" on affected variables