patch 8.2.1632: not checking the context of test_fails()

Problem:    Not checking the context of test_fails().
Solution:   Add the line number and context arguments.  Give error if
            assert_fails() argument types are wrong.
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index bf81bbe..ae8f329 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -524,7 +524,7 @@
 
 def Test_error_in_nested_function()
   # Error in called function requires unwinding the call stack.
-  assert_fails('FuncWithForwardCall()', 'E1096:', 1, 'FuncWithForwardCall')
+  assert_fails('FuncWithForwardCall()', 'E1096:', '', 1, 'FuncWithForwardCall')
 enddef
 
 def Test_return_type_wrong()