Use anyhow more idiomatically (#31052)

https://github.com/zed-industries/zed/issues/30972 brought up another
case where our context is not enough to track the actual source of the
issue: we get a general top-level error without inner error.

The reason for this was `.ok_or_else(|| anyhow!("failed to read HEAD
SHA"))?; ` on the top level.

The PR finally reworks the way we use anyhow to reduce such issues (or
at least make it simpler to bubble them up later in a fix).
On top of that, uses a few more anyhow methods for better readability.

* `.ok_or_else(|| anyhow!("..."))`, `map_err` and other similar error
conversion/option reporting cases are replaced with `context` and
`with_context` calls
* in addition to that, various `anyhow!("failed to do ...")` are
stripped with `.context("Doing ...")` messages instead to remove the
parasitic `failed to` text
* `anyhow::ensure!` is used instead of `if ... { return Err(...); }`
calls
* `anyhow::bail!` is used instead of `return Err(anyhow!(...));`

Release Notes:

- N/A

crates/collab/src/api/billing.rs

@@ -1,4 +1,4 @@
-use anyhow::{Context, anyhow, bail};
+use anyhow::{Context as _, bail};
 use axum::{
     Extension, Json, Router,
     extract::{self, Query},
@@ -89,7 +89,7 @@ async fn get_billing_preferences(
         .db
         .get_user_by_github_user_id(params.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let billing_customer = app.db.get_billing_customer_by_user_id(user.id).await?;
     let preferences = app.db.get_billing_preferences(user.id).await?;
@@ -138,7 +138,7 @@ async fn update_billing_preferences(
         .db
         .get_user_by_github_user_id(body.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let billing_customer = app.db.get_billing_customer_by_user_id(user.id).await?;
 
@@ -241,7 +241,7 @@ async fn list_billing_subscriptions(
         .db
         .get_user_by_github_user_id(params.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let subscriptions = app.db.get_billing_subscriptions(user.id).await?;
 
@@ -307,7 +307,7 @@ async fn create_billing_subscription(
         .db
         .get_user_by_github_user_id(body.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let Some(stripe_billing) = app.stripe_billing.clone() else {
         log::error!("failed to retrieve Stripe billing object");
@@ -432,7 +432,7 @@ async fn manage_billing_subscription(
         .db
         .get_user_by_github_user_id(body.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let Some(stripe_client) = app.stripe_client.clone() else {
         log::error!("failed to retrieve Stripe client");
@@ -454,7 +454,7 @@ async fn manage_billing_subscription(
         .db
         .get_billing_customer_by_user_id(user.id)
         .await?
-        .ok_or_else(|| anyhow!("billing customer not found"))?;
+        .context("billing customer not found")?;
     let customer_id = CustomerId::from_str(&customer.stripe_customer_id)
         .context("failed to parse customer ID")?;
 
@@ -462,7 +462,7 @@ async fn manage_billing_subscription(
         .db
         .get_billing_subscription_by_id(body.subscription_id)
         .await?
-        .ok_or_else(|| anyhow!("subscription not found"))?;
+        .context("subscription not found")?;
     let subscription_id = SubscriptionId::from_str(&subscription.stripe_subscription_id)
         .context("failed to parse subscription ID")?;
 
@@ -559,7 +559,7 @@ async fn manage_billing_subscription(
                         None
                     }
                 })
-                .ok_or_else(|| anyhow!("No subscription item to update"))?;
+                .context("No subscription item to update")?;
 
             Some(CreateBillingPortalSessionFlowData {
                 type_: CreateBillingPortalSessionFlowDataType::SubscriptionUpdateConfirm,
@@ -653,7 +653,7 @@ async fn migrate_to_new_billing(
         .db
         .get_user_by_github_user_id(body.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let old_billing_subscriptions_by_user = app
         .db
@@ -732,13 +732,13 @@ async fn sync_billing_subscription(
         .db
         .get_user_by_github_user_id(body.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let billing_customer = app
         .db
         .get_billing_customer_by_user_id(user.id)
         .await?
-        .ok_or_else(|| anyhow!("billing customer not found"))?;
+        .context("billing customer not found")?;
     let stripe_customer_id = billing_customer
         .stripe_customer_id
         .parse::<stripe::CustomerId>()
@@ -1031,13 +1031,13 @@ async fn sync_subscription(
     let billing_customer =
         find_or_create_billing_customer(app, stripe_client, subscription.customer)
             .await?
-            .ok_or_else(|| anyhow!("billing customer not found"))?;
+            .context("billing customer not found")?;
 
     if let Some(SubscriptionKind::ZedProTrial) = subscription_kind {
         if subscription.status == SubscriptionStatus::Trialing {
             let current_period_start =
                 DateTime::from_timestamp(subscription.current_period_start, 0)
-                    .ok_or_else(|| anyhow!("No trial subscription period start"))?;
+                    .context("No trial subscription period start")?;
 
             app.db
                 .update_billing_customer(
@@ -1243,7 +1243,7 @@ async fn get_monthly_spend(
         .db
         .get_user_by_github_user_id(params.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let Some(llm_db) = app.llm_db.clone() else {
         return Err(Error::http(
@@ -1311,7 +1311,7 @@ async fn get_current_usage(
         .db
         .get_user_by_github_user_id(params.github_user_id)
         .await?
-        .ok_or_else(|| anyhow!("user not found"))?;
+        .context("user not found")?;
 
     let feature_flags = app.db.get_user_flags(user.id).await?;
     let has_extended_trial = feature_flags