[sarankumar1325]

Description of your changes

Fixes #143

When a shellCommand exits non-zero, the fatal result reads shellCmd "..." for "..." failed with : exit status N, with nothing after "failed with". The message is built from exec.ExitError.Stderr, but Go only fills that in from Cmd.Output when Cmd.Stderr is unset. RunFunction sets cmd.Stderr and calls cmd.Run(), so the field is always nil.

This PR builds the message from serr instead. That is the stderr the function already captured and writes to stderrField. With echo 'error output' >&2; exit 1, the result is now ... failed with error output: exit status 1.

This covers only the message part of the issue. The question of whether a non-zero exit should stay Fatal (which drops the desired XR, so stderrField never lands) is a design decision for maintainers and is left unchanged.

TestRunFunction ignores Result.message (protocmp.IgnoreFields), so its expected messages aren't checked. I added TestRunFunctionFailureMessage, which asserts the full message for a failing command with stderr and one without. It fails on main and passes with the fix.

I have:

• Read and followed Crossplane's
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• Added or updated unit tests for my change.

Tested with go test ./..., go vet ./... and golangci-lint run (v2.14.0, 0 issues).

This change was prepared with help from an AI coding assistant. I reviewed it.