`--missing error` does not work with 'include'

[n-arakawa]

Missing vars in included file does not rise error with --missing error.

$ more a.in b.in | cat
::::::::::::::
a.in
::::::::::::::
{{- include "b.in" -}}
::::::::::::::
b.in
::::::::::::::
var1={{.var1}}
$ frep  --no-sys-env --missing error  --overwrite b.in:b.out 
fatal: render template error, caused:

   template: b.in:1:7: executing "b.in" at <.var1>: map has no entry for key "var1"

$ frep  --no-sys-env --missing error --overwrite a.in:a.out 
$ cat a.out 
var1=<no value>
$