I know the return statement returns immediately regardless of conditional blocks, and that's fine. The problem is that the error message is unexpected.

layouts/all.html

{{ if true }}
  {{ return true }}
{{ else }}
  {{ return false }}
{{ end }}

The error message is:

execute of template failed: template: all.html:2:5: executing "all.html" at : wrong number of args for return: want 0 got 1