[clang-tools-extra] [clang-doc] Refactor error handling to use ExitOnError (PR #141699)

[Samarth Narang via cfe-commits]

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@@ -300,7 +297,7 @@ Example usage for a project using a compile commands database:
                       "these files and continue:\n"
                    << toString(std::move(Err)) << "\n";
     else {
-      llvm::errs() << toString(std::move(Err)) << "\n";
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snarang181 wrote:

Sounds like a good refactoring practice, but do we have enough usecases? I suppose if it's just two calls, I doubt if the code size increase + extra function call is worth it? 

https://github.com/llvm/llvm-project/pull/141699