$tmpl error message improvement

[ghost]

V version: 0.3.1 f8a28b5
OS: ArchLinux

What did you do?

template.txt

@name

fn foo(){
	name := 'abc'
	$tmpl('template.txt')
}

fn bar(){
	$tmpl('template.txt')
}

fn main(){
}

What did you expect to see?
Line number both in V file and template file.

What did you see instead?
Only template file line number.

> v run .
template.txt:9:32: error: undefined ident: `name`

[bogen85]

There are other confusing error message for $tmpl. See #16154