Syntax highlighting issue when @ appears as first character after line continuation when indexing is present

[alexr00]

• Editor name and version: VS Code 1.71

• Platform: Any

• Color scheme: NA

• MagicPython version:

• A sreenshot:
  I would expect syntax highlighting to be the same irrespective of whether the line is broken before or after the @ operator.
  

• 5-10 lines of surrounding code:

# Define variables so pylance doesn't complain.
long_variable_name = other_long_variable_name = 1

long_variable_name \
    @ other_long_variable_name['some_index']

long_variable_name @ \
    other_long_variable_name['some_index']

Originally from @tillahoffmann in microsoft/vscode#161435