IR: Fix error rendering on IR symbol binding conflict

it could be called with uninitialized `owner` parameter, leading
to the NPE on render

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/symbols/impl/IrPrivateSymbolBase.kt

@@ -61,7 +61,7 @@ abstract class IrBindableSymbolBase<out D : DeclarationDescriptor, B : IrSymbolO
         if (_owner == null) {
             _owner = owner
         } else {
-            throw IllegalStateException("${javaClass.simpleName} is already bound: ${owner.render()}")
+            throw IllegalStateException("${javaClass.simpleName} is already bound: ${_owner?.render()}")
         }
     }
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/symbols/impl/IrPublicSymbolBase.kt

@@ -55,7 +55,7 @@ abstract class IrBindablePublicSymbolBase<out D : DeclarationDescriptor, B : IrS
         if (_owner == null) {
             _owner = owner
         } else {
-            throw IllegalStateException("${javaClass.simpleName} for $signature is already bound: ${owner.render()}")
+            throw IllegalStateException("${javaClass.simpleName} for $signature is already bound: ${_owner?.render()}")
         }
     }