Clarify errors in main() coming from the governance canister client. (

#232)

I spent 10 minutes trying to grep for the error, to no avail.  When I
had to spend another 5 minutes adding `panic()`s to the code in order
to suss this one out, I decided to do something about it.

rs/cli/src/main.rs

@@ -36,7 +36,16 @@ async fn main() -> Result<(), anyhow::Error> {
     let mut cli_opts = cli::Opts::parse();
     let mut cmd = cli::Opts::command();
 
-    let governance_canister_v = governance_canister_version(cli_opts.network.get_url()).await?;
+    let governance_canister_v = match governance_canister_version(cli_opts.network.get_url()).await {
+        Ok(c) => c,
+        Err(e) => {
+            return Err(anyhow::anyhow!(
+                "While determining the governance canister version: {}",
+                e
+            ))
+        }
+    };
+
     let governance_canister_version = governance_canister_v.stringified_hash;
 
     let target_network = cli_opts.network.clone();
@@ -52,9 +61,10 @@ async fn main() -> Result<(), anyhow::Error> {
                 .expect("failed")
         });
     });
+
     let srv = rx.recv().unwrap();
 
-    ic_admin::with_ic_admin(governance_canister_version.into(), async {
+    let r = ic_admin::with_ic_admin(governance_canister_version.into(), async {
 
         // Start of actually doing stuff with commands.
         if cli_opts.network == Network::Staging {
@@ -303,11 +313,11 @@ async fn main() -> Result<(), anyhow::Error> {
             }
         }
     })
-    .await?;
+    .await;
 
     srv.stop(false).await;
 
-    Ok(())
+    r
 }
 
 // Construct MinNakamotoCoefficients from an array (slice) of ["key=value"], and