How to change NODE_ENV for netlify functions

I’m not setting CONTEXT var just trying to retrieve the value of process.env.CONTEXT, which is undefinied. My code looks like:

if (process.env.CONTEXT === 'production') {
  host = process.env.GATSBY_HOST_URL
  clientId = process.env.GATSBY_GITHUB_CLIENT_ID
  password = process.env.GATSBY_FUNCTION_PASSWORD
} else if (process.env.CONTEXT === 'development') {
  host = process.env.GATSBY_DEV_HOST_URL
  clientId = process.env.GATSBY_DEV_GITHUB_CLIENT_ID
  password = process.env.GATSBY_DEV_FUNCTION_PASSWORD
}

When I run netlify dev I expect process.env.CONTEXT to equal to development and in the rest of the cases I expect it to be production.

netlify.toml:

[settings]
  ID = "fbe445b2-665a-4b6b-befb-98c0249e523e"
[build]
  base = "/"
  publish = "public"
  command = "yarn build"
  functions = ".netlify/functions"
[build.environment]
  NODE_VERSION = "11.5.0"
  YARN_VERSION = "1.3.2"
  YARN_FLAGS = "--no-ignore-optional"
[context.production]
  NODE_ENV = "production"
[context.deploy-preview]
  NODE_ENV = "production"
[context.branch-deploy] 
  NODE_ENV = "production"

The rest of the code can be found in the repo

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