[clang] [clang-format] Fix crashes when the macro expansion is empty (PR #119428)

[Björn Schäpers via cfe-commits]

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@@ -233,6 +233,10 @@ MacroExpander::expand(FormatToken *ID,
   if (Result.size() > 1) {
     ++Result[0]->MacroCtx->StartOfExpansion;
     ++Result[Result.size() - 2]->MacroCtx->EndOfExpansion;
+  } else {
+    // If the macro expansion is empty, mark the start and end
----------------
HazardyKnusperkeks wrote:

```suggestion
    // If the macro expansion is empty, mark the start and end.
```

https://github.com/llvm/llvm-project/pull/119428