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/agent/src/agent_panel.rs

@@ -1212,12 +1212,7 @@ impl AgentPanel {
         window: &mut Window,
         cx: &mut Context<Self>,
     ) {
-        let Some(workspace) = self
-            .workspace
-            .upgrade()
-            .ok_or_else(|| anyhow!("workspace dropped"))
-            .log_err()
-        else {
+        let Some(workspace) = self.workspace.upgrade() else {
             return;
         };
 

crates/agent/src/buffer_codegen.rs

@@ -1,7 +1,7 @@
 use crate::context::ContextLoadResult;
 use crate::inline_prompt_editor::CodegenStatus;
 use crate::{context::load_context, context_store::ContextStore};
-use anyhow::Result;
+use anyhow::{Context as _, Result};
 use assistant_settings::AssistantSettings;
 use client::telemetry::Telemetry;
 use collections::HashSet;
@@ -419,16 +419,16 @@ impl CodegenAlternative {
             if start_buffer.remote_id() == end_buffer.remote_id() {
                 (start_buffer.clone(), start_buffer_offset..end_buffer_offset)
             } else {
-                return Err(anyhow::anyhow!("invalid transformation range"));
+                anyhow::bail!("invalid transformation range");
             }
         } else {
-            return Err(anyhow::anyhow!("invalid transformation range"));
+            anyhow::bail!("invalid transformation range");
         };
 
         let prompt = self
             .builder
             .generate_inline_transformation_prompt(user_prompt, language_name, buffer, range)
-            .map_err(|e| anyhow::anyhow!("Failed to generate content prompt: {}", e))?;
+            .context("generating content prompt")?;
 
         let context_task = self.context_store.as_ref().map(|context_store| {
             if let Some(project) = self.project.upgrade() {

crates/agent/src/context_store.rs

@@ -2,7 +2,7 @@ use std::ops::Range;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use anyhow::{Result, anyhow};
+use anyhow::{Context as _, Result, anyhow};
 use assistant_context_editor::AssistantContext;
 use collections::{HashSet, IndexSet};
 use futures::{self, FutureExt};
@@ -142,17 +142,12 @@ impl ContextStore {
         remove_if_exists: bool,
         cx: &mut Context<Self>,
     ) -> Result<Option<AgentContextHandle>> {
-        let Some(project) = self.project.upgrade() else {
-            return Err(anyhow!("failed to read project"));
-        };
-
-        let Some(entry_id) = project
+        let project = self.project.upgrade().context("failed to read project")?;
+        let entry_id = project
             .read(cx)
             .entry_for_path(project_path, cx)
             .map(|entry| entry.id)
-        else {
-            return Err(anyhow!("no entry found for directory context"));
-        };
+            .context("no entry found for directory context")?;
 
         let context_id = self.next_context_id.post_inc();
         let context = AgentContextHandle::Directory(DirectoryContextHandle {

crates/agent/src/history_store.rs

@@ -1,6 +1,6 @@
 use std::{collections::VecDeque, path::Path, sync::Arc};
 
-use anyhow::{Context as _, anyhow};
+use anyhow::Context as _;
 use assistant_context_editor::{AssistantContext, SavedContextMetadata};
 use chrono::{DateTime, Utc};
 use futures::future::{TryFutureExt as _, join_all};
@@ -130,7 +130,10 @@ impl HistoryStore {
                                         .boxed()
                                 })
                                 .unwrap_or_else(|_| {
-                                    async { Err(anyhow!("no thread store")) }.boxed()
+                                    async {
+                                        anyhow::bail!("no thread store");
+                                    }
+                                    .boxed()
                                 }),
                             SerializedRecentEntry::Context(id) => context_store
                                 .update(cx, |context_store, cx| {
@@ -140,7 +143,10 @@ impl HistoryStore {
                                         .boxed()
                                 })
                                 .unwrap_or_else(|_| {
-                                    async { Err(anyhow!("no context store")) }.boxed()
+                                    async {
+                                        anyhow::bail!("no context store");
+                                    }
+                                    .boxed()
                                 }),
                         });
                     let entries = join_all(entries)

crates/agent/src/thread.rs

@@ -1630,7 +1630,7 @@ impl Thread {
                                         CompletionRequestStatus::Failed {
                                             code, message, request_id
                                         } => {
-                                            return Err(anyhow!("completion request failed. request_id: {request_id}, code: {code}, message: {message}"));
+                                            anyhow::bail!("completion request failed. request_id: {request_id}, code: {code}, message: {message}");
                                         }
                                         CompletionRequestStatus::UsageUpdated {
                                             amount, limit

crates/agent/src/thread_store.rs

@@ -419,7 +419,7 @@ impl ThreadStore {
             let thread = database
                 .try_find_thread(id.clone())
                 .await?
-                .ok_or_else(|| anyhow!("no thread found with ID: {id:?}"))?;
+                .with_context(|| format!("no thread found with ID: {id:?}"))?;
 
             let thread = this.update_in(cx, |this, window, cx| {
                 cx.new(|cx| {
@@ -699,20 +699,14 @@ impl SerializedThread {
                 SerializedThread::VERSION => Ok(serde_json::from_value::<SerializedThread>(
                     saved_thread_json,
                 )?),
-                _ => Err(anyhow!(
-                    "unrecognized serialized thread version: {}",
-                    version
-                )),
+                _ => anyhow::bail!("unrecognized serialized thread version: {version:?}"),
             },
             None => {
                 let saved_thread =
                     serde_json::from_value::<LegacySerializedThread>(saved_thread_json)?;
                 Ok(saved_thread.upgrade())
             }
-            version => Err(anyhow!(
-                "unrecognized serialized thread version: {:?}",
-                version
-            )),
+            version => anyhow::bail!("unrecognized serialized thread version: {version:?}"),
         }
     }
 }