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

[Paul Kirth via cfe-commits]

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@@ -0,0 +1,12 @@
+// Test: Invalid output path (%t is a file, not a directory)
+// RUN: rm -rf %t && echo "not a dir" > %t
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ilovepi wrote:

we don't need this echo. you can just `touch %t` to the same effect.

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