[clang-tools-extra] [clang-doc] Fix nullptr dereference in JSONGenerator::insertComment (PR #173336)

[Erick Velez via cfe-commits]

https://github.com/evelez7 created https://github.com/llvm/llvm-project/pull/173336

The `if` statements in `insertComment` didn't check whether or not the comment JSON object was a nullptr before dereferencing it. This crash only happened when running clang-doc on larger codebases, like `clang`.

>From cc0c16657a09df9359f983864fe32beedc931b8f Mon Sep 17 00:00:00 2001
From: Erick Velez <erickvelez7 at gmail.com>
Date: Mon, 22 Dec 2025 22:33:12 -0800
Subject: [PATCH] [clang-doc] Fix nullptr dereference in
 JSONGenerator::insertComment

The `if` statements in `insertComment` didn't check whether or not the
comment JSON object was a nullptr before dereferencing it. This crash
only happened when running clang-doc on larger codebases, like `clang`.
---
 clang-tools-extra/clang-doc/JSONGenerator.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clang-doc/JSONGenerator.cpp b/clang-tools-extra/clang-doc/JSONGenerator.cpp
index 9c384ed7eeade..6dec347ed0bd0 100644
--- a/clang-tools-extra/clang-doc/JSONGenerator.cpp
+++ b/clang-tools-extra/clang-doc/JSONGenerator.cpp
@@ -98,11 +98,12 @@ static void insertComment(Object &Description, json::Value &Comment,
   // The comment has a Children array for the actual text, with meta attributes
   // alongside it in the Object.
   if (auto *Obj = Comment.getAsObject()) {
-    if (auto *Children = Obj->getArray("Children"); Children->empty())
+    if (auto *Children = Obj->getArray("Children");
+        Children && Children->empty())
       return;
   }
   // The comment is just an array of text comments.
-  else if (auto *Array = Comment.getAsArray(); Array->empty()) {
+  else if (auto *Array = Comment.getAsArray(); Array && Array->empty()) {
     return;
   }