[clang] Fix a crash introduced by 3d5e9ab by adding a nullptr check. (PR #90301)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Ryosuke Niwa (rniwa)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/90301.diff


1 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp (+1-1) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
index 741f336761589f..96bae0de65a5b1 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedCallArgsChecker.cpp
@@ -54,7 +54,7 @@ class UncountedCallArgsChecker
       bool shouldVisitImplicitCode() const { return false; }
 
       bool TraverseDecl(Decl *D) {
-        if (isa<ClassTemplateDecl>(D) && isRefType(safeGetName(D)))
+        if (D && isa<ClassTemplateDecl>(D) && isRefType(safeGetName(D)))
           return true;
         return RecursiveASTVisitor<LocalVisitor>::TraverseDecl(D);
       }

``````````

</details>


https://github.com/llvm/llvm-project/pull/90301