fix: getPropertyName handles sourceless nodes

src/NodeParser/TypeLiteralNodeParser.ts

@@ -78,10 +78,19 @@ export class TypeLiteralNodeParser implements SubNodeParser {
     protected getPropertyName(propertyName: ts.PropertyName): string {
         if (propertyName.kind === ts.SyntaxKind.ComputedPropertyName) {
             const symbol = this.typeChecker.getSymbolAtLocation(propertyName);
+
             if (symbol) {
                 return symbol.getName();
             }
         }
-        return propertyName.getText();
+
+        try {
+            return propertyName.getText();
+        } catch {
+            // When propertyName was programmatically created, it doesn't have a source file.
+            // Then, getText() will throw an error. But, for programmatically created nodes,`
+            // `escapedText` is available.
+            return (propertyName as ts.Identifier).escapedText as string;
+        }
     }
 }