Fix crash caused by empty user keyword arguments

d-biehl · web-flow · commit b135d6ae5634 · 2022-01-28T12:12:54.000+02:00
Fixes #4181.
diff --git a/atest/robot/parsing/user_keyword_settings.robot b/atest/robot/parsing/user_keyword_settings.robot
@@ -106,6 +106,11 @@ Small typo should provide recommendation
     ...    Non-existing setting 'Doc Umentation'. Did you mean:
     ...    ${SPACE*4}Documentation
 
+Invalid empty line continuation in arguments should throw an error    
+    Error in File    3   parsing/user_keyword_settings.robot     206
+    ...    Creating keyword 'Invalid empty line continuation in arguments should throw an error' failed: Invalid argument specification: Invalid argument syntax ''.
+
+
 *** Keywords ***
 Verify Documentation
     [Arguments]    ${doc}    ${test}=${TEST NAME}
diff --git a/atest/testdata/parsing/user_keyword_settings.robot b/atest/testdata/parsing/user_keyword_settings.robot
@@ -202,3 +202,7 @@ Invalid failing
 Small typo should provide recommendation
     [Doc Umentation]
     No Operation
+
+Invalid empty line continuation in arguments should throw an error
+    [Arguments]
+    ...
diff --git a/src/robot/running/arguments/argumentparser.py b/src/robot/running/arguments/argumentparser.py
@@ -196,13 +196,13 @@ def _validate_arg(self, arg):
         return arg, default
 
     def _is_kwargs(self, arg):
-        return arg[0] == '&'
+        return arg and arg[0] == '&'
 
     def _format_kwargs(self, kwargs):
         return kwargs[2:-1]
 
     def _is_varargs(self, arg):
-        return arg[0] == '@'
+        return arg and arg[0] == '@'
 
     def _is_kw_only_separator(self, arg):
         return arg == '@{}'
