Fix PsiInvalidElementAccessException

Author: sxhya

src/main/kotlin/org/arend/injection/InjectedArendEditor.kt

@@ -386,7 +386,8 @@ abstract class InjectedArendEditor(
             var scope: Scope? = null
             var ref: Referable? = null
             if (unresolvedRef != null || error.hasExpressions()) {
-                scope = (data as? PsiElement)?.ancestor<ArendCompositeElement>()?.scope?.let { CachingScope.make(it) }
+                val compositeElement = (data as? PsiElement)?.ancestor<ArendCompositeElement>()
+                if (compositeElement?.isValid == true) scope = compositeElement.scope.let { CachingScope.make(it) }
             }
             if (unresolvedRef != null && scope != null) {
                 ref = ExpressionResolveNameVisitor.resolve(unresolvedRef, scope)

src/main/kotlin/org/arend/psi/ext/ArendCompositeElement.kt

@@ -47,6 +47,8 @@ interface ArendSourceNode: ArendCompositeElement, Abstract.SourceNode {
 }
 
 fun getArendScope(element: ArendCompositeElement): Scope {
+    if (!element.isValid)
+        return EmptyScope.INSTANCE
     val sourceNode = element.ancestor<ArendSourceNode>()?.topmostEquivalentSourceNode ?: return (element.containingFile as? ArendFile)?.scope ?: EmptyScope.INSTANCE
     ((sourceNode as? ArendLongName)?.parent as? ArendDocReference)?.let { return it.scope }