CLI: make sure we do not load WalletDB while another process is accessing it

- do not load WalletDB in order to check keystore password
- do not allow --offline commands while a daemon is running

run_electrum

@@ -152,27 +152,19 @@ def init_cmdline(config_options, wallet_path, server, *, config: 'SimpleConfig')
         print_stderr("Exposing a single private key can compromise your entire wallet!")
         print_stderr("In particular, DO NOT use 'redeem private key' services proposed by third parties.")
 
-    # will we need a password
-    if not storage.is_encrypted():
-        db = WalletDB(storage.read(), manual_upgrades=False)
-        use_encryption = db.get('use_encryption')
-    else:
-        use_encryption = True
-
     # commands needing password
     if ((cmd.requires_wallet and storage.is_encrypted() and server is False)\
        or (cmdname == 'load_wallet' and storage.is_encrypted())\
-       or (cmd.requires_password and use_encryption)):
+       or cmd.requires_password):
         if storage.is_encrypted_with_hw_device():
             # this case is handled later in the control flow
             password = None
-        elif config.get('password'):
+        elif config.get('password') is not None:
             password = config.get('password')
+            if password == '':
+                password = None
         else:
-            password = prompt_password('Password:', False)
-            if not password:
-                print_msg("Error: Password required")
-                sys_exit(1)
+            password = prompt_password('Password:', None)
     else:
         password = None
 
@@ -512,6 +504,12 @@ def handle_cmd(*, cmdname: str, config: 'SimpleConfig', config_options: dict):
             if cmd.requires_network:
                 print_msg("This command cannot be run offline")
                 sys_exit(1)
+            lockfile = daemon.get_lockfile(config)
+            if os.path.exists(lockfile):
+                print_stderr("Daemon already running (lockfile detected)")
+                print_stderr("Run 'electrum stop' to stop the daemon.")
+                print_stderr("Run this command without --offline to interact with the daemon")
+                sys_exit(1)
             init_cmdline(config_options, wallet_path, False, config=config)
             plugins = init_plugins(config, 'cmdline')
             coro = run_offline_command(config, config_options, plugins)