feat: Remove compile time environment variable

code/crates-tui-tutorial-app/src/crates_io_api_helper.rs

@@ -4,7 +4,7 @@ use crates_io_api::CratesQuery;
 use tokio::sync::mpsc::UnboundedSender;
 
 use crate::action::Action;
-use color_eyre::Result;
+use color_eyre::{eyre::Context, Result};
 
 // ANCHOR: search_parameters
 /// Represents the parameters needed for fetching crates asynchronously.
@@ -42,7 +42,7 @@ pub async fn request_search_results(
 /// into a result pattern.
 fn create_client() -> Result<crates_io_api::AsyncClient, String> {
     // ANCHOR: client
-    let email = env!("CRATES_TUI_TUTORIAL_APP_MYEMAIL");
+    let email = std::env::var("CRATES_TUI_TUTORIAL_APP_MYEMAIL").context("Need to set CRATES_TUI_TUTORIAL_APP_MYEMAIL environment variable to proceed").unwrap();
 
     let user_agent = format!("crates-tui ({email})");
     let rate_limit = std::time::Duration::from_millis(1000);

src/content/docs/tutorials/crates-tui/crates-io-api.md

@@ -16,7 +16,7 @@ This `AsyncClient` can be initialized as follows:
 
 In order to initialize the client, we have to provide an email as the user agent. In the source code
 of this tutorial, we read an email from the environment variable `CRATES_TUI_TUTORIAL_APP_MYEMAIL`
-at compile time.
+at run time.
 
 :::tip