Answers for "element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'typeo"

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{}'. No index signature with a parameter of type 'string' was found on type '{}'.ts(7053)

//This will fail typecheck
const map = {};
map[someString] = "hello";

//This will pass typecheck
const map: {[key:string]: string} = {};
map[someString] = "hello";

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type { }. No index signature with a parameter of type 'string' was found on type '{ develop: string; staging: string; production: string; }'.ts(7053)

const DNATranscriber = {
    G: 'C',
    C: 'G',
    T: 'A',
    A: 'U'
};

export default class Transcriptor {
    toRna(dna: string) {
        const codons = [...dna];
        if (!isValidSequence(codons)) {
            throw Error('invalid sequence');
        }
        const transcribedRNA = codons.map(codon => DNATranscriber[codon]);
        return transcribedRNA;
    }
}

function isValidSequence(values: string[]): values is Array<keyof typeof DNATranscriber> {
    return values.every(isValidCodon);
}
function isValidCodon(value: string): value is keyof typeof DNATranscriber {
    return value in DNATranscriber;
}