UnsupportedOperation exception thrown with IntelliJ 2020.2

[philwebb]

This exception is thrown when our formatter is active: https://github.com/JetBrains/intellij-community/blob/9bbaa4b940f823b33359911df9f5f9363c549064/platform/core-api/src/com/intellij/psi/codeStyle/CodeStyleManager.java#L351