This is a problem with package [solidity-parser-antlr](https://github.com/federicobond/solidity-parser-antlr) with is a dependency of [sol-merger](https://github.com/RyuuGan/sol-merger) which flattener depends on.
This is a problem with package solidity-parser-antlr with is a dependency of sol-merger which flattener depends on.