Don't print root_cause if there's only one error in the chain

If there's only one error in the chain, it prints:

    error: no matches for event ID: no matches for event ID

Now, it will print:

    error: no matches for event ID

and:

    error: unable to open OAuth secret file: Not a directory (os error 20)

1 files changed, 7 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 5298c30..36c2b27 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -42,7 +42,13 @@ async fn main() {
     match run().await {
         Ok(_) => (),
         Err(e) => {
-            eprintln!("error: {}: {}", e, e.root_cause());
+            eprint!("error");
+
+            for cause in e.chain() {
+                eprint!(": {}", cause);
+            }
+
+            eprintln!();
 
             process::exit(exitcode::SOFTWARE);
         },