Copy: Filter out invalid elements to prevent PsiInvalidElementAccessException

#KT-12747 Fixed
(cherry picked from commit 4a0a440)

ChangeLog.md

@@ -248,6 +248,7 @@
 - [`KT-10687`](https://youtrack.jetbrains.com/issue/KT-10687) Qualify property references to avoid shadowing by parameters
 - [`KT-12543`](https://youtrack.jetbrains.com/issue/KT-12543) Qualify property references with 'this' to avoid renaming conflicts
 - [`KT-12732`](https://youtrack.jetbrains.com/issue/KT-12732) Copy default parameter values to overriding function which is renamed by Java reference while its base function is unchanged
+- [`KT-12747`](https://youtrack.jetbrains.com/issue/KT-12747) Fix exception on file copy
 
 #### Java to Kotlin converter
 

idea/src/org/jetbrains/kotlin/idea/refactoring/copy/CopyKotlinFileHandler.kt

@@ -27,7 +27,7 @@ class CopyKotlinFileHandler : CopyHandlerDelegateBase() {
 
     private fun adjustElements(elements: Array<out PsiElement>): Array<PsiElement>? {
         return elements
-                .map { it.containingFile as? KtFile ?: return null }
+                .map { (if (it.isValid) it.containingFile as? KtFile else null) ?: return null }
                 .toTypedArray()
     }