Check empty input for login

Signed-off-by: hi-rustin <rustin.liu@gmail.com>

src/cargo/ops/registry.rs

@@ -764,7 +764,11 @@ pub fn registry_login(
                 .with_context(|| "failed to read stdin")?;
             // Automatically remove `cargo login` from an inputted token to
             // allow direct pastes from `registry.host()`/me.
-            line.replace("cargo login", "").trim().to_string()
+            line.replace("cargo login", "").trim().to_string();
+            if line.is_empty() {
+                bail!("please provide a non-empty token");
+            }
+            line
         }
     };