skylark.Call: panics with nil function about skylark HOT 1 CLOSED

As you point out, nil is not a valid skylark.Value, so passing nil to Call is a user error, that is, a bug in the Go program, not an expected error caused by evaluation of the Skylark function. A panic is thus the correct way to report the mistake. (Returning an error would cause the bug to remain latent.)

I have no problem with adding an explicit precondition check such as if fn == nil { panic("Call(fn=nil)") } if it would cause a violation to be discovered sooner, or more clearly, than it otherwise would, but in this instance fn is dereferenced eagerly by fn.Type(), and the failure can be unambiguously attributed to the nil pointer as there is no other operation on that line that can fail.

So the program is working as intended.

from skylark.