Throw exception instead of force unwrapping Metal handles when initialising MetalRedrawer. (#704)

* Throw exception instead of force unwrapping Metal handles

* Update skiko/src/macosMain/kotlin/org/jetbrains/skiko/redrawer/MetalRedrawer.macos.kt
Co-authored-by: Ivan Matkov <ivan.matkov@jetbrains.com>

* Update based on review feedback

* Remove redundant this

* Remove unneeded imports

---------
Co-authored-by: Elijah Semyonov <elijah.semyonov@jetbrains.com>
Co-authored-by: Ivan Matkov <ivan.matkov@jetbrains.com>

skiko/src/iosMain/kotlin/org/jetbrains/skiko/redrawer/MetalRedrawer.ios.kt

@@ -28,8 +28,8 @@ internal class MetalRedrawer(
     override val renderInfo: String get() = contextHandler.rendererInfo()
 
     private var isDisposed = false
-    internal val device = MTLCreateSystemDefaultDevice()!!
-    private val queue = device.newCommandQueue()!!
+    internal val device = MTLCreateSystemDefaultDevice() ?: throw IllegalStateException("Metal is not supported on this system")
+    private val queue = device.newCommandQueue() ?: throw IllegalStateException("Couldn't create Metal command queue")
     private var currentDrawable: CAMetalDrawableProtocol? = null
     private val metalLayer = MetalLayer()
     private val frameListener: NSObject = FrameTickListener {

skiko/src/macosMain/kotlin/org/jetbrains/skiko/redrawer/MetalRedrawer.macos.kt

@@ -39,8 +39,8 @@ internal class MacOsMetalRedrawer(
     override val renderInfo: String get() = contextHandler.rendererInfo()
 
     private var isDisposed = false
-    internal val device = MTLCreateSystemDefaultDevice()!!
-    private val queue = device.newCommandQueue()!!
+    internal val device = MTLCreateSystemDefaultDevice() ?: throw IllegalStateException("Metal is not supported on this system")
+    private val queue = device.newCommandQueue() ?: throw IllegalStateException("Couldn't create Metal command queue")
     private var currentDrawable: CAMetalDrawableProtocol? = null
     private val metalLayer = MetalLayer()