diff --git a/korgw/src/macosMain/kotlin/com/soywiz/korgw/DefaultGameWindowMacos.kt b/korgw/src/macosMain/kotlin/com/soywiz/korgw/DefaultGameWindowMacos.kt
index 960b06f654..9041e5010c 100644
--- a/korgw/src/macosMain/kotlin/com/soywiz/korgw/DefaultGameWindowMacos.kt
+++ b/korgw/src/macosMain/kotlin/com/soywiz/korgw/DefaultGameWindowMacos.kt
@@ -600,22 +600,24 @@ class MyDefaultGameWindow : GameWindow() {
             val arena = Arena()
             val displayLink = arena.alloc<CVDisplayLinkRefVar>()
 
+            private fun checkDisplayLink(code: Int) {
+                if (code != kCVReturnSuccess) internalException(code)
+            }
+
             fun createDisplayLink(): Boolean {
                 //println("createDisplayLink[1]")
-                val displayID = CGMainDisplayID()
-                val error = CVDisplayLinkCreateWithCGDisplay(displayID, displayLink.ptr)
-                //println("createDisplayLink[2]")
-                if (error == kCVReturnSuccess) {
-                    //println("createDisplayLink[3]")
-
-                    CVDisplayLinkSetOutputCallback(displayLink.value, staticCFunction(::displayCallback), gameWindowStableRef.asCPointer())
-                    CVDisplayLinkStart(displayLink.value)
-                    //println("createDisplayLink[4]")
-                    return true
-                } else {
-                    return false
+                return try {
+                    checkDisplayLink(CVDisplayLinkCreateWithCGDisplay(CGMainDisplayID(), displayLink.ptr))
+                    checkDisplayLink(CVDisplayLinkSetOutputCallback(displayLink.value, staticCFunction(::displayCallback), gameWindowStableRef.asCPointer()))
+                    checkDisplayLink(CVDisplayLinkStart(displayLink.value))
+                    true
+                } catch (e: InternalException) {
+                    if (displayLink.value != null) {
+                        CVDisplayLinkRelease(displayLink.value)
+                    }
+                    e.printStackTrace()
+                    false
                 }
-                //println("createDisplayLink[5]")
             }
 
             private fun timer(timer: NSTimer?) {
@@ -645,7 +647,7 @@ class MyDefaultGameWindow : GameWindow() {
     override suspend fun clipboardRead(): ClipboardData? {
         val pasteboard = NSPasteboard.generalPasteboard
         val items = pasteboard.pasteboardItems as? List<NSPasteboardItem>?
-        if (items == null || items.isEmpty()) return null
+        if (items.isNullOrEmpty()) return null
         return items.last().stringForType(NSPasteboardTypeString)?.let { TextClipboardData(it) }
     }
 }
@@ -656,8 +658,13 @@ private val atomicDisplayLinkContext = AtomicReference<COpaquePointer?>(null)
 
 @SharedImmutable
 val doDisplayCallbackRender: () -> Unit = {
-    val gameWindow = atomicDisplayLinkContext.value?.asStableRef<MyDefaultGameWindow>()
-    gameWindow?.get()?.doRender(update = true)
+    try {
+        initRuntimeIfNeeded()
+        val gameWindow = atomicDisplayLinkContext.value?.asStableRef<MyDefaultGameWindow>()
+        gameWindow?.get()?.doRender(update = true)
+    } catch (e: Throwable) {
+        e.printStackTrace()
+    }
 }
 
 @Suppress("UNUSED_PARAMETER")
diff --git a/korio/src/commonMain/kotlin/com/soywiz/korio/lang/Exceptions.kt b/korio/src/commonMain/kotlin/com/soywiz/korio/lang/Exceptions.kt
index 08d929038a..82ed10d7b4 100644
--- a/korio/src/commonMain/kotlin/com/soywiz/korio/lang/Exceptions.kt
+++ b/korio/src/commonMain/kotlin/com/soywiz/korio/lang/Exceptions.kt
@@ -1,6 +1,7 @@
 package com.soywiz.korio.lang
 
 import com.soywiz.klogger.Console
+import com.soywiz.krypto.encoding.*
 
 expect open class IOException(msg: String) : Exception
 expect open class EOFException(msg: String) : IOException
@@ -11,6 +12,7 @@ open class MalformedInputException(msg: String) : Exception(msg) {
 
 class FileAlreadyExistsException(msg: String) : IOException(msg)
 
+class InternalException(val code: Int) : Exception("Internal Exception with code $code (0x${code.hex})")
 class InvalidOperationException(str: String = "Invalid Operation") : Exception(str)
 class OutOfBoundsException(index: Int = -1, str: String = "Out Of Bounds") : Exception(str)
 class KeyNotFoundException(str: String = "Key Not Found") : Exception(str)
@@ -32,6 +34,7 @@ val invalidArg: Nothing get() = throw InvalidArgumentException()
 val unreachable: Nothing get() = throw UnreachableException()
 val reserved: Nothing get() = throw ReservedException()
 
+fun internalException(code: Int): Nothing = throw InternalException(code)
 fun deprecated(msg: String): Nothing = throw DeprecatedException(msg)
 fun mustValidate(msg: String): Nothing = throw MustValidateCodeException(msg)
 fun noImpl(msg: String): Nothing = throw NotImplementedException(msg)
@@ -39,8 +42,7 @@ fun invalidOp(msg: String): Nothing = throw InvalidOperationException(msg)
 fun invalidArg(msg: String): Nothing = throw InvalidArgumentException(msg)
 fun unreachable(msg: String): Nothing = throw UnreachableException(msg)
 fun reserved(msg: String): Nothing = throw ReservedException(msg)
-fun unsupported(msg: String): Nothing = throw UnsupportedOperationException(msg)
-fun unsupported(): Nothing = throw UnsupportedOperationException("unsupported")
+fun unsupported(msg: String = "unsupported"): Nothing = throw UnsupportedOperationException(msg)
 fun invalidArgument(msg: String): Nothing = throw InvalidArgumentException(msg)
 fun unexpected(msg: String): Nothing = throw UnexpectedException(msg)
 fun malformedInput(msg: String): Nothing = throw MalformedInputException(msg)
diff --git a/krypto/src/commonMain/kotlin/com/soywiz/krypto/encoding/Hex.kt b/krypto/src/commonMain/kotlin/com/soywiz/krypto/encoding/Hex.kt
index c381cf0d4b..79499dd1a0 100644
--- a/krypto/src/commonMain/kotlin/com/soywiz/krypto/encoding/Hex.kt
+++ b/krypto/src/commonMain/kotlin/com/soywiz/krypto/encoding/Hex.kt
@@ -76,7 +76,15 @@ val String.unhexIgnoreSpaces: ByteArray get() = buildString {
 val String.unhex get() = Hex.decode(this)
 val ByteArray.hex get() = Hex.encodeLower(this)
 
+/**
+ * Returns this number as a hexadecimal string in the format:
+ * 0xWWXXYYZZ
+ */
 val Int.hex: String get() = "0x$shex"
+/**
+ * Returns this number as a hexadecimal string in the format:
+ * WWXXYYZZ
+ */
 val Int.shex: String
     get() = buildString(8) {
         for (n in 0 until 8) {