Adds check to parse_command_line_template to catch options that don't have trailing field

pydra/compose/shell/builder.py

@@ -512,6 +512,9 @@
                 f"Found unknown token {token!r} in command line template: {template}"
             )
 
+    if option:
+        raise ValueError(f"Found an option without a field: {option!r}")
+
     remaining_pos = remaining_positions(arguments, len(arguments) + 1, 1)
 
     for argument in arguments:

pydra/compose/shell/tests/test_shell_fields.py

@@ -984,6 +984,13 @@ def test_shell_missing_executable_dynamic():
         )
 
 
+def test_shell_trailing_option_fail():
+
+    with pytest.raises(ValueError, match="Found an option without a field"):
+
+        shell.define("ls <directory:generic/directory> --unparameterized-option ")
+
+
 def test_shell_help1():
 
     Shelly = shell.define(