Error when I define the languageDef in the UserConfig

[karcagtamas]

Hi all. I ran into a problem and I don't really know what is the solution.
I've configured the monaco-editor and provided the user config to it. I would like to add langugeDef with monarchLanguage settings for Kotlin. When I define the configs I got error:

TypeError: Cannot read properties of undefined (reading 'match')
    at _MonarchModernTokensCollector.emit (editor.api.js:369:38)
    at MonarchTokenizer2._myTokenize (editor.api.js:810:37)
    at MonarchTokenizer2._tokenize (editor.api.js:522:25)
    at MonarchTokenizer2.tokenizeEncoded (editor.api.js:514:35)
    at safeTokenize (textModelTokens.js:324:37)
    at TokenizerWithStateStoreAndTextModel.updateTokensUntilLine (textModelTokens.js:44:23)
    at DefaultBackgroundTokenizer._tokenizeOneInvalidLine (textModelTokens.js:402:39)
    at DefaultBackgroundTokenizer._backgroundTokenizeForAtLeast1ms (textModelTokens.js:383:46)
    at execute (textModelTokens.js:365:18)
    at DefaultBackgroundTokenizer._backgroundTokenizeWithDeadline (textModelTokens.js:373:9)
    at errors.js:10:29

And the error row, in the MonarchModernTokensCollector class.

const metadata = this._theme.match(this._currentLanguageId, type) | MetadataConsts.BALANCED_BRACKETS_MASK;

The currently set theme is undefined. I've tried define one, but i dont know the proper use case for that. The methods what I found, caused server re-initialized error.

Do you have any idea what can cause the problem?

[CGNonofr]

It looks like you've registered the theme service override, isn't it? Then you can use monarch grammars anymore