Refine MissingParameter error messages

Improved error handling by refining the MissingParameter exceptions in __init__.py. The changes provide more specific error messages when label or namespace parameters are missing for better debugging.

docker_injector/__init__.py

@@ -112,17 +112,16 @@ def shutdown_child(process: subprocess.Popen):
 @click.option("--cmd", prompt=False, default=lambda: os.environ.get("INJECTOR_CMD", None),
               help="The command to run in the namespace")
 def inject(label, require, ns, proc, cmd):
-
     if label is None:
-        raise MissingParameter("Label is not specified")
+        raise MissingParameter("Label is not specified", param=label)
     l = re.split("[:=]", label)
     name = l[0]
     if len(l) == 2:
         value = l[1]
     else:
         value = None
     if ns is None:
-        raise MissingParameter("Namespaces are not specified")
+        raise MissingParameter("Namespaces are not specified", param=ns)
     nslist = ns.split(',')
     client = docker.from_env()
     if value is None: