Zero value of os.PathError causes panic when printing

[Brian Candler]

Is this intentional?

https://play.golang.org/p/ylXlkOq2sID

Result I get in browser:

&{0}

%!v(PANIC=Error method: runtime error: invalid memory address or nil pointer dereference) 

[Axel Wagner]

I don't know if it's intentional, but I think it's expected. The panic happens because it tries to stringify the underlying error, which is nil. I would say the creation of a packages error types are the purview of that package. I don't think you can, generally, expect that their zero values are valid.

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[Brian Candler]

However, the zero value itself is printable.  It's only a pointer to the zero value which panics.

https://play.golang.org/p/LhmhdeHTb0m

[Axel Wagner]

That's because the `Error` method is declared on the pointer, not the value. So `fmt` uses its reflect-based printing for structs.

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[Brian Candler]

Ah OK, so fmt uses Error() if it exists? Makes sense then, thanks.

BTW, I received additional (and badly-formatted) copies of your messages from "N0JfR25EemNRTjZ...@devo.memo.com", relayed via a server 149.72.164.25 which appears to be sendgrid.com / joylabs.com.  The message itself gives no way for me to unsubscribe from this service, nor does the memo.com website.  Do you happen to know anything about this?