fix: processing example is failing when example contains jsdoc annota…

…ted export (#1170)

Fixes #1161

The code to process statements was making some incorrect assumptions
about how the AST looks like.
This fix is making it more resilient to unexpected AST structures.

---

By submitting this pull request, I confirm that my contribution is made
under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

---------

Signed-off-by: Momo Kornher <kornherm@amazon.co.uk>
(cherry picked from commit b41e905)

src/fixtures.ts

@@ -186,7 +186,7 @@ function sidelineImports(source: string): {
       statement.kind === SyntaxKind.ImportDeclaration ||
       statement.kind === SyntaxKind.ImportEqualsDeclaration ||
       (statement.kind === SyntaxKind.VariableStatement &&
-        statement.getChildAt(0).getChildAt(0).kind === SyntaxKind.DeclareKeyword)
+        statement.getChildAt(0)?.getChildAt(0)?.kind === SyntaxKind.DeclareKeyword)
     ) {
       imports += statement.getFullText(sourceFile);
     } else {

test/fixtures.test.ts

@@ -49,4 +49,22 @@ const val = new Cls();
 // Code snippet ended before !hide marker above
 `);
   });
+
+  // https://github.com/aws/jsii-rosetta/issues/1161
+  test('regression: can parse source with jsdoc annotated export', () => {
+    const snippet = {
+      visibleSource: `
+        /**
+         * JSDoc
+         */
+        export const foo = "bar";
+      `,
+      location,
+      parameters: {
+        [SnippetParameters.$PROJECT_DIRECTORY]: 'test',
+      },
+    };
+
+    expect(fixturize(snippet)).toEqual(expect.objectContaining(snippet));
+  });
 });