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/channel/src/channel_chat.rs

@@ -1,5 +1,5 @@
 use crate::{Channel, ChannelStore};
-use anyhow::{Result, anyhow};
+use anyhow::{Context as _, Result};
 use client::{
     ChannelId, Client, Subscription, TypedEnvelope, UserId, proto,
     user::{User, UserStore},
@@ -170,15 +170,16 @@ impl ChannelChat {
         message: MessageParams,
         cx: &mut Context<Self>,
     ) -> Result<Task<Result<u64>>> {
-        if message.text.trim().is_empty() {
-            Err(anyhow!("message body can't be empty"))?;
-        }
+        anyhow::ensure!(
+            !message.text.trim().is_empty(),
+            "message body can't be empty"
+        );
 
         let current_user = self
             .user_store
             .read(cx)
             .current_user()
-            .ok_or_else(|| anyhow!("current_user is not present"))?;
+            .context("current_user is not present")?;
 
         let channel_id = self.channel_id;
         let pending_id = ChannelMessageId::Pending(post_inc(&mut self.next_pending_message_id));
@@ -215,7 +216,7 @@ impl ChannelChat {
             });
             let response = request.await?;
             drop(outgoing_message_guard);
-            let response = response.message.ok_or_else(|| anyhow!("invalid message"))?;
+            let response = response.message.context("invalid message")?;
             let id = response.id;
             let message = ChannelMessage::from_proto(response, &user_store, cx).await?;
             this.update(cx, |this, cx| {
@@ -470,7 +471,7 @@ impl ChannelChat {
                     });
                     let response = request.await?;
                     let message = ChannelMessage::from_proto(
-                        response.message.ok_or_else(|| anyhow!("invalid message"))?,
+                        response.message.context("invalid message")?,
                         &user_store,
                         cx,
                     )
@@ -531,10 +532,7 @@ impl ChannelChat {
         mut cx: AsyncApp,
     ) -> Result<()> {
         let user_store = this.update(&mut cx, |this, _| this.user_store.clone())?;
-        let message = message
-            .payload
-            .message
-            .ok_or_else(|| anyhow!("empty message"))?;
+        let message = message.payload.message.context("empty message")?;
         let message_id = message.id;
 
         let message = ChannelMessage::from_proto(message, &user_store, &mut cx).await?;
@@ -566,10 +564,7 @@ impl ChannelChat {
         mut cx: AsyncApp,
     ) -> Result<()> {
         let user_store = this.update(&mut cx, |this, _| this.user_store.clone())?;
-        let message = message
-            .payload
-            .message
-            .ok_or_else(|| anyhow!("empty message"))?;
+        let message = message.payload.message.context("empty message")?;
 
         let message = ChannelMessage::from_proto(message, &user_store, &mut cx).await?;
 
@@ -753,10 +748,7 @@ impl ChannelMessage {
                 .collect(),
             timestamp: OffsetDateTime::from_unix_timestamp(message.timestamp as i64)?,
             sender,
-            nonce: message
-                .nonce
-                .ok_or_else(|| anyhow!("nonce is required"))?
-                .into(),
+            nonce: message.nonce.context("nonce is required")?.into(),
             reply_to_message_id: message.reply_to_message_id,
             edited_at,
         })

crates/channel/src/channel_store.rs

@@ -1,7 +1,7 @@
 mod channel_index;
 
 use crate::{ChannelMessage, channel_buffer::ChannelBuffer, channel_chat::ChannelChat};
-use anyhow::{Result, anyhow};
+use anyhow::{Context as _, Result, anyhow};
 use channel_index::ChannelIndex;
 use client::{ChannelId, Client, ClientSettings, Subscription, User, UserId, UserStore};
 use collections::{HashMap, HashSet, hash_map};
@@ -332,9 +332,7 @@ impl ChannelStore {
         cx.spawn(async move |this, cx| {
             if let Some(request) = request {
                 let response = request.await?;
-                let this = this
-                    .upgrade()
-                    .ok_or_else(|| anyhow!("channel store dropped"))?;
+                let this = this.upgrade().context("channel store dropped")?;
                 let user_store = this.update(cx, |this, _| this.user_store.clone())?;
                 ChannelMessage::from_proto_vec(response.messages, &user_store, cx).await
             } else {
@@ -482,7 +480,7 @@ impl ChannelStore {
                         .spawn(async move |this, cx| {
                             let channel = this.update(cx, |this, _| {
                                 this.channel_for_id(channel_id).cloned().ok_or_else(|| {
-                                    Arc::new(anyhow!("no channel for id: {}", channel_id))
+                                    Arc::new(anyhow!("no channel for id: {channel_id}"))
                                 })
                             })??;
 
@@ -514,7 +512,7 @@ impl ChannelStore {
                 }
             }
         };
-        cx.background_spawn(async move { task.await.map_err(|error| anyhow!("{}", error)) })
+        cx.background_spawn(async move { task.await.map_err(|error| anyhow!("{error}")) })
     }
 
     pub fn is_channel_admin(&self, channel_id: ChannelId) -> bool {
@@ -578,9 +576,7 @@ impl ChannelStore {
                 })
                 .await?;
 
-            let channel = response
-                .channel
-                .ok_or_else(|| anyhow!("missing channel in response"))?;
+            let channel = response.channel.context("missing channel in response")?;
             let channel_id = ChannelId(channel.id);
 
             this.update(cx, |this, cx| {
@@ -752,7 +748,7 @@ impl ChannelStore {
                 })
                 .await?
                 .channel
-                .ok_or_else(|| anyhow!("missing channel in response"))?;
+                .context("missing channel in response")?;
             this.update(cx, |this, cx| {
                 let task = this.update_channels(
                     proto::UpdateChannels {