drawPageAsPNG generates base64 with newline character

[lnfel]

Describe the bug Generating a PNG image using drawPageAsPNG has newline after data:image/png;base64,

To Reproduce

import { createMuPdf } from "mupdf-js"

let preview = []

// Initialize mupdf and call mupdfGeneratePNG
async function mupdfPreview(file) {
  const mupdf = await createMuPdf()
  const fileArrayBuffer = await file.arrayBuffer()
  const fileBuffer = new Uint8Array(fileArrayBuffer)
  const pdf = mupdf.load(fileBuffer)
  const pages = mupdf.countPages(pdf)
  return await mupdfGeneratePNG(mupdf, pdf, file, pages)
}

// Generate previews for pdf pages and return array of base64 PNGs
async function mupdfGeneratePNG(mupdf, pdf, file, pages) {
  return new Promise((resolve, reject) => {
    try {
      for (let i = 1; i < pages; i++) {
        const base64Image = mupdf.drawPageAsPNG(pdf, i, 10) // issue is here
        preview.push(image)
      }
      
      resolve(preview)
    } catch (error) {
      console.log(error)
      reject(error)
    }
  })
}

// Handle file input on change event
async function onChange(event) {
  const files = event.target.files
  Array.from(files).forEach(async (file) => {
      if (file.type === 'application/pdf') {
        await mupdfPreview(file)
      }
  })
}

// Listen for input file change
const input = document.querySelector('[type="file"]')
input.addEventListener('change', onChange)

Expected behavior drawPageAsPNG should return a single line base64 string like:

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA...

Actual behavior base64 string has newline after data:image/png;base64,

data:image/png;base64,
iVBORw0KGgoAAAANSUhEUgAA...

# in some environments the newline would be escaped and become `%0A`, resulting to:
data:image/png;base64,%0AiVBORw0KGgoAAAANSUhEUgAA...

Log output Paste outputs from your terminal or browser logs to help explain your problem.

Screenshots

Desktop (please complete the following information):

• OS: Linux and MacOS
• OS Version: Ubuntu 22.04 LTS (GNU/Linux 5.15.0-1031-aws x86_64) and MacOS Catalina version 10.15.7
• Browser (or Node) Chrome and Node
• Browser (or Node) version: Chrome Version 110.0.5481.177 (Official Build) (x86_64) and Node v18.14.2
• Architecture: x86_64

Smartphone (please complete the following information): Not applicable

Additional context Nothing