Ignore type aliases in code generation.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -106,6 +106,9 @@ class ClassCodegen private constructor(val irClass: IrClass, val context: JvmBac
             is IrAnonymousInitializer -> {
                 // skip
             }
+            is IrTypeAlias -> {
+                // skip
+            }
             is IrClass -> {
                 ClassCodegen(declaration, context).generate()
             }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.descriptors.impl.TypeAliasConstructorDescriptor
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.IrTypeAlias
 import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.util.render
@@ -306,6 +307,10 @@ class ExpressionCodegen(
         return none()
     }
 
+    override fun visitTypeAlias(declaration: IrTypeAlias, data: BlockInfo): StackValue {
+        return none()
+    }
+
     override fun visitVararg(expression: IrVararg, data: BlockInfo): StackValue {
         val size = expression.elements.size
         mv.iconst(size)