Method handleSupSubscript

src/Parser.ts:285–307

* Handle a subscript or superscript with nice errors.

(
        name: string,   // For error reporting.
    )

     * Handle a subscript or superscript with nice errors.
     */
    handleSupSubscript(
        name: string,   // For error reporting.
    ): AnyParseNode {
        const symbolToken = this.fetch();
        const symbol = symbolToken.text;
        this.consume();
        this.consumeSpaces(); // ignore spaces before sup/subscript argument

        // Skip over allowed internal nodes such as \relax
        let group: AnyParseNode | null | undefined;
        do {
            group = this.parseGroup(name);
        } while (group?.type === "internal");

        if (!group) {
            throw new ParseError(
                "Expected group after '" + symbol + "'",
                symbolToken
            );
        }

        return group;
    }

    /**
     * Converts the textual input of an unsupported command into a text node