bin/tau: print info if the workspace is not configured

bin/tau/tau-cli/src/main.rs

@@ -335,6 +335,8 @@ async fn main() -> Result<()> {
             TauSubcommand::Switch { workspace } => {
                 if tau.switch_ws(workspace.clone()).await? {
                     println!("You are now on \"{}\" workspace", workspace);
+                } else {
+                    println!("Workspace \"{}\" is not configured", workspace);
                 }
 
                 Ok(())

bin/tau/taud/src/jsonrpc.rs

@@ -326,6 +326,7 @@ impl JsonRpcInterface {
             *s = ws
         } else {
             warn!("Workspace \"{}\" is not configured", ws);
+            return Ok(json!(false))
         }
 
         Ok(json!(true))