Report SDK SSH config load failures

src/client.rs

@@ -165,8 +165,7 @@ impl DoshClientBuilder {
             .or(host_config.port)
             .unwrap_or(self.client.config.dosh_port);
         let ssh_port = host_config.ssh_port.or(self.client.config.ssh_port);
-        let ssh_config =
+        let ssh_config = load_sdk_ssh_config(host_config.ssh_config.as_deref(), ssh_port)?;
-            load_sdk_ssh_config(host_config.ssh_config.as_deref(), ssh_port).unwrap_or_default();
         let requested_user = self
             .user
             .clone()
@@ -735,6 +734,14 @@ mod tests {
         assert!(parsed.identities_only);
     }
 
+    #[test]
+    fn sdk_ssh_config_without_alias_does_not_shell_out() {
+        assert_eq!(
+            load_sdk_ssh_config(None, Some(2222)).unwrap(),
+            SdkSshConfig::default()
+        );
+    }
+
     #[test]
     fn sdk_identity_paths_follow_cli_precedence_and_identities_only() {
         let dir = tempfile::tempdir().unwrap();