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/cli/src/main.rs

@@ -169,7 +169,7 @@ fn main() -> Result<()> {
             "To retrieve the system specs on the command line, run the following command:",
             &format!("{} --system-specs", path.display()),
         ];
-        return Err(anyhow::anyhow!(msg.join("\n")));
+        anyhow::bail!(msg.join("\n"));
     }
 
     #[cfg(all(
@@ -255,11 +255,10 @@ fn main() -> Result<()> {
         }
     }
 
-    if let Some(_) = args.dev_server_token {
-        return Err(anyhow::anyhow!(
-            "Dev servers were removed in v0.157.x please upgrade to SSH remoting: https://zed.dev/docs/remote-development"
-        ))?;
-    }
+    anyhow::ensure!(
+        args.dev_server_token.is_none(),
+        "Dev servers were removed in v0.157.x please upgrade to SSH remoting: https://zed.dev/docs/remote-development"
+    );
 
     let sender: JoinHandle<anyhow::Result<()>> = thread::spawn({
         let exit_status = exit_status.clone();
@@ -400,7 +399,7 @@ mod linux {
         time::Duration,
     };
 
-    use anyhow::anyhow;
+    use anyhow::{Context as _, anyhow};
     use cli::FORCE_CLI_MODE_ENV_VAR_NAME;
     use fork::Fork;
 
@@ -417,9 +416,7 @@ mod linux {
                 path.to_path_buf().canonicalize()?
             } else {
                 let cli = env::current_exe()?;
-                let dir = cli
-                    .parent()
-                    .ok_or_else(|| anyhow!("no parent path for cli"))?;
+                let dir = cli.parent().context("no parent path for cli")?;
 
                 // libexec is the standard, lib/zed is for Arch (and other non-libexec distros),
                 // ./zed is for the target directory in development builds.
@@ -428,8 +425,8 @@ mod linux {
                 possible_locations
                     .iter()
                     .find_map(|p| dir.join(p).canonicalize().ok().filter(|path| path != &cli))
-                    .ok_or_else(|| {
-                        anyhow!("could not find any of: {}", possible_locations.join(", "))
+                    .with_context(|| {
+                        format!("could not find any of: {}", possible_locations.join(", "))
                     })?
             };
 
@@ -759,7 +756,7 @@ mod windows {
 
 #[cfg(target_os = "macos")]
 mod mac_os {
-    use anyhow::{Context as _, Result, anyhow};
+    use anyhow::{Context as _, Result};
     use core_foundation::{
         array::{CFArray, CFIndex},
         base::TCFType as _,
@@ -800,9 +797,10 @@ mod mac_os {
         let cli_path = std::env::current_exe()?.canonicalize()?;
         let mut app_path = cli_path.clone();
         while app_path.extension() != Some(OsStr::new("app")) {
-            if !app_path.pop() {
-                return Err(anyhow!("cannot find app bundle containing {:?}", cli_path));
-            }
+            anyhow::ensure!(
+                app_path.pop(),
+                "cannot find app bundle containing {cli_path:?}"
+            );
         }
         Ok(app_path)
     }