[environment]
HUGO_VERSION = "0.26"
  
[context.production.environment]
HUGO_ENV = "production"


[context.production.environment]
HUGO_VERSION = "0.26"
HUGO_ENV = "production"

[context.deploy-preview.environment]
HUGO_VERSION = "0.26"

Set HUGO_VERSION for deploy preview
Set HUGO_VERSION for deploy preview

Not sure how to set a default ...