async function main() {
}
The above code produces this in Pygments 2.6.1:

The issue is caused by https://github.com/pygments/pygments/blob/master/pygments/lexers/javascript.py#L511
# Match stuff like: function() {...}
(r'([a-zA-Z_?.$][\w?.$]*)\(\) \{', Name.Other, 'slashstartsregex'),
which tags the () { as Name.Other. So I suggest change it to
# Match stuff like: function() {...}
(r'([a-zA-Z_?.$][\w?.$]*)(?=\(\) \{)', Name.Other, 'slashstartsregex'),