export function addBase64HeaderToPng(base64Data: string) { if (typeof base64Data !== "string" || !base64Data) { return "" } if (base64Data.startsWith('data:')) { if (base64Data.startsWith('data:image/png;base64,')) { return base64Data } else { throw new Error("fatal: the input string is NOT a PNG image!") } } else { return `data:image/png;base64,${base64Data}` } }