Support lateinit var interpretation

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/IrInterpreter.kt

@@ -570,19 +570,17 @@ class IrInterpreter(private val irBuiltIns: IrBuiltIns, private val bodyMap: Map
     }
 
     private fun interpretVariable(expression: IrVariable): ExecutionResult {
-        expression.initializer?.interpret()?.check { return it } ?: return Next
+        if (expression.initializer == null) {
+            return Next.apply { stack.addVar(Variable(expression.symbol)) }
+        }
+        expression.initializer?.interpret()?.check { return it } //?: return Next
         stack.addVar(Variable(expression.symbol, stack.popReturnValue()))
         return Next
     }
 
     private fun interpretSetVariable(expression: IrSetValue): ExecutionResult {
         expression.value.interpret().check { return it }
-
-        if (stack.contains(expression.symbol)) {
-            stack.getVariable(expression.symbol).apply { this.state = stack.popReturnValue() }
-        } else {
-            stack.addVar(Variable(expression.symbol, stack.popReturnValue()))
-        }
+        stack.getVariable(expression.symbol).apply { this.state = stack.popReturnValue() }
         return Next
     }
 

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/stack/Variable.kt

@@ -9,4 +9,10 @@ import org.jetbrains.kotlin.ir.interpreter.state.State
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 
 // TODO maybe switch to typealias and use map instead of list
-internal data class Variable(val symbol: IrSymbol, var state: State)
+internal data class Variable(val symbol: IrSymbol) {
+    lateinit var state: State
+
+    constructor(symbol: IrSymbol, state: State) : this(symbol) {
+        this.state = state
+    }
+}