getTextOfPropertyName: Assert input value is a PropertyName (#21981)

Author: Andy

src/compiler/checker.ts

@@ -21909,11 +21909,13 @@ namespace ts {
                 // check private/protected variable access
                 const parent = node.parent.parent;
                 const parentType = getTypeForBindingElementParent(parent);
-                const name = node.propertyName || <Identifier>node.name;
-                const property = getPropertyOfType(parentType, getTextOfPropertyName(name));
-                markPropertyAsReferenced(property, /*nodeForCheckWriteOnly*/ undefined, /*isThisAccess*/ false); // A destructuring is never a write-only reference.
-                if (parent.initializer && property) {
-                    checkPropertyAccessibility(parent, parent.initializer, parentType, property);
+                const name = node.propertyName || node.name;
+                if (!isBindingPattern(name)) {
+                    const property = getPropertyOfType(parentType, getTextOfPropertyName(name));
+                    markPropertyAsReferenced(property, /*nodeForCheckWriteOnly*/ undefined, /*isThisAccess*/ false); // A destructuring is never a write-only reference.
+                    if (parent.initializer && property) {
+                        checkPropertyAccessibility(parent, parent.initializer, parentType, property);
+                    }
                 }
             }
 

src/compiler/utilities.ts

@@ -570,17 +570,15 @@ namespace ts {
     export function getTextOfPropertyName(name: PropertyName): __String {
         switch (name.kind) {
             case SyntaxKind.Identifier:
-                return (<Identifier>name).escapedText;
+                return name.escapedText;
             case SyntaxKind.StringLiteral:
             case SyntaxKind.NumericLiteral:
-                return escapeLeadingUnderscores((<LiteralExpression>name).text);
+                return escapeLeadingUnderscores(name.text);
             case SyntaxKind.ComputedPropertyName:
-                if (isStringOrNumericLiteral((<ComputedPropertyName>name).expression)) {
-                    return escapeLeadingUnderscores((<LiteralExpression>(<ComputedPropertyName>name).expression).text);
-                }
+                return isStringOrNumericLiteral(name.expression) ? escapeLeadingUnderscores(name.expression.text) : undefined;
+            default:
+                Debug.assertNever(name);
         }
-
-        return undefined;
     }
 
     export function entityNameToString(name: EntityNameOrEntityNameExpression): string {