https://github.com/mozilla/pdf.js/issues/6397#issuecomment-164954332 Would have been a lot easier to find had there been an assertion checking that string16 didn't go out of bounds of the 16bit number.

COPY: 0x10,
  MODIFY_ANNOTATIONS: 0x20,
  FILL_INTERACTIVE_FORMS: 0x100,
  COPY_FOR_ACCESSIBILITY: 0x200,
  ASSEMBLE: 0x400,
  PRINT_HIGH_QUALITY: 0x800,
};
const TextRenderingMode = {
  FILL: 0,
  STROKE: 1,
  FILL_STROKE: 2,
  INVISIBLE: 3,
  FILL_ADD_TO_PATH: 4,
  STROKE_ADD_TO_PATH: 5,
  FILL_STROKE_ADD_TO_PATH: 6,
  ADD_TO_PATH: 7,
  FILL_STROKE_MASK: 3,
  ADD_TO_PATH_FLAG: 4,
};
const ImageKind = {
  GRAYSCALE_1BPP: 1,
  RGB_24BPP: 2,
  RGBA_32BPP: 3,
};
const AnnotationType = {
  TEXT: 1,
  LINK: 2,
  FREETEXT: 3,
  LINE: 4,
  SQUARE: 5,