[llvm] [lit] Clean up internal shell parse errors with ScriptFatal (PR #68496)

[Alexander Richardson via llvm-commits]

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@@ -1009,7 +1020,8 @@ def formatOutput(title, data, limit=None):
     return out
 
 
-# Normally returns out, err, exitCode, timeoutInfo.
+# Always either returns the tuple (out, err, exitCode, timeoutInfo) or raises a
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arichardson wrote:

How about using a type annotation for the function signature instead of this comment? Then it can be checked by type checker tools as well as IDEs.

https://github.com/llvm/llvm-project/pull/68496