fix: support renaming a property to a private identifier

Closes #1198

packages/ts-morph/src/manipulation/nodeHandlers/StraightReplacementNodeHandler.ts

@@ -17,6 +17,13 @@ export class StraightReplacementNodeHandler implements NodeHandler {
     handleNode(currentNode: Node, newNode: ts.Node, newSourceFile: ts.SourceFile) {
         /* istanbul ignore if */
         if (currentNode.getKind() !== newNode.kind) {
+            // support a private identifier and identifier being swapped
+            const kinds = [currentNode.getKind(), newNode.kind];
+            if (kinds.includes(ts.SyntaxKind.Identifier) && kinds.includes(ts.SyntaxKind.PrivateIdentifier)) {
+                currentNode.forget();
+                return;
+            }
+
             throw new errors.InvalidOperationError(`Error replacing tree! Perhaps a syntax error was inserted `
                 + `(Current: ${currentNode.getKindName()} -- New: ${getSyntaxKindName(newNode.kind)}).`);
         }

packages/ts-morph/src/tests/issues/1198tests.ts

@@ -0,0 +1,35 @@
+import { expect } from "chai";
+import { Project } from "../../Project";
+
+describe.only("tests for issue #1198", () => {
+    it("should not have issues when renaming private identifier", () => {
+        const project = new Project({ useInMemoryFileSystem: true });
+        const sourceFile = project.createSourceFile("mod.ts", `class Foo {
+  private one: string;
+  private two: string;
+}`);
+        const classDecl = sourceFile.getClasses()[0];
+        for (const property of classDecl.getInstanceProperties()) {
+            const name = property.getName();
+            property.toggleModifier("private", false);
+            property.rename(`#${name}`);
+        }
+
+        expect(sourceFile.getText()).to.equal(`class Foo {
+  #one: string;
+  #two: string;
+}`);
+
+        // now swap them back
+        for (const property of classDecl.getInstanceProperties()) {
+            const name = property.getName().replace(/^#/, "");
+            property.rename(`${name}`);
+            property.toggleModifier("private", true);
+        }
+
+        expect(sourceFile.getText()).to.equal(`class Foo {
+  private one: string;
+  private two: string;
+}`);
+    });
+});