Assertion Failure When Extension Throws Error

[hediet]

Implementation:

public async resolveCustomTextEditor(
		document: TextDocument,
		webviewPanel: WebviewPanel,
		token: CancellationToken
	): Promise<void> {
		throw new Error("invalid document extension!");
}

Error message when I open such a custom text editor:

I think the extension error message should be shown instead and not the internal assertion failure message.