From 7e862bbc41a73aa5af349015bbf893a00b132482 Mon Sep 17 00:00:00 2001
From: SUZUKI Sosuke <aosukeke@gmail.com>
Date: Sat, 13 Jan 2024 04:12:55 +0900
Subject: [PATCH] Fix formatting error on member chain (#15915)

---
 changelog_unreleased/javascript/15915.md         | 14 ++++++++++++++
 src/language-js/utils/index.js                   | 10 ++++++++++
 .../__snapshots__/jsfmt.spec.js.snap             | 16 ++++++++++++++++
 tests/format/js/chain-expression/issue-15912.js  |  3 +++
 4 files changed, 43 insertions(+)
 create mode 100644 changelog_unreleased/javascript/15915.md
 create mode 100644 tests/format/js/chain-expression/issue-15912.js

diff --git a/changelog_unreleased/javascript/15915.md b/changelog_unreleased/javascript/15915.md
new file mode 100644
index 000000000..b493ac1b2
--- /dev/null
+++ b/changelog_unreleased/javascript/15915.md
@@ -0,0 +1,14 @@
+#### Fix formatting error on member chain (#15915 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+test().test2().test2(thing?.something);
+
+// Prettier stable
+TypeError: Cannot read properties of undefined (reading 'type')
+
+// Prettier main
+test().test2().test2(thing?.something);
+
+```
diff --git a/src/language-js/utils/index.js b/src/language-js/utils/index.js
index b3bfe1646..7ba6692b7 100644
--- a/src/language-js/utils/index.js
+++ b/src/language-js/utils/index.js
@@ -405,6 +405,16 @@ function isTestCall(node, parent) {
 /** @return {(node: Node) => boolean} */
 const skipChainExpression = (fn) => (node) => {
   if (node?.type === "ChainExpression") {
+    // @ts-expect-error
+    if (!node.object) {
+      // @ts-expect-error
+      node.object = node.expression.object;
+    }
+    // @ts-expect-error
+    if (!node.property) {
+      // @ts-expect-error
+      node.property = node.expression.property;
+    }
     node = node.expression;
   }
 
diff --git a/tests/format/js/chain-expression/__snapshots__/jsfmt.spec.js.snap b/tests/format/js/chain-expression/__snapshots__/jsfmt.spec.js.snap
index 4bd0c7234..e34333448 100644
--- a/tests/format/js/chain-expression/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/format/js/chain-expression/__snapshots__/jsfmt.spec.js.snap
@@ -81,6 +81,22 @@ logger.log(
 ================================================================================
 `;
 
+exports[`issue-15912.js format 1`] = `
+====================================options=====================================
+parsers: ["babel", "typescript", "flow"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+test()
+  .test2()
+  .test2(thing?.something);
+
+=====================================output=====================================
+test().test2().test2(thing?.something);
+
+================================================================================
+`;
+
 exports[`test.js format 1`] = `
 ====================================options=====================================
 parsers: ["babel", "typescript", "flow"]
diff --git a/tests/format/js/chain-expression/issue-15912.js b/tests/format/js/chain-expression/issue-15912.js
new file mode 100644
index 000000000..19a6fd6a8
--- /dev/null
+++ b/tests/format/js/chain-expression/issue-15912.js
@@ -0,0 +1,3 @@
+test()
+  .test2()
+  .test2(thing?.something);