Example output from psd.js. You can see how it errors at the end.

gistfile1.txt

➜  psd.js git:(master) ✗ coffee test/test.coffee
Beginning parsing

### Header ###
{ sig: '8BPS',
  version: 1,
  r0: 0,
  r1: 0,
  r2: 0,
  r3: 0,
  r4: 0,
  r5: 0,
  channels: 4,
  rows: 128,
  cols: 128,
  depth: 8,
  mode: 3,
  modename: 'RGBColor' }
Skipped color mode data with 0 bytes

### Resources ###
Resource:  { at: 34,
  type: '8BIM',
  id: 1061,
  namelen: 0,
  name: '',
  short: '',
  size: 16,
  rdesc: '[undefined]' }
Resource:  { at: 62,
  type: '8BIM',
  id: 1060,
  namelen: 0,
  name: '',
  short: '',
  size: 14112,
  rdesc: '[undefined]' }
Resource:  { at: 14186,
  type: '8BIM',
  id: 1082,
  namelen: 0,
  name: '',
  short: '',
  size: 147,
  rdesc: '[undefined]' }
Resource:  { at: 14346,
  type: '8BIM',
  id: 1083,
  namelen: 0,
  name: '',
  short: '',
  size: 434,
  rdesc: '[undefined]' }
Resource:  { at: 14792,
  type: '8BIM',
  id: 1005,
  namelen: 0,
  name: '',
  short: '',
  size: 16,
  rdesc: '[ResolutionInfo]' }
Resource:  { at: 14820,
  type: '8BIM',
  id: 1062,
  namelen: 0,
  name: '',
  short: '',
  size: 14,
  rdesc: '[undefined]' }
Resource:  { at: 14846,
  type: '8BIM',
  id: 1006,
  namelen: 0,
  name: '',
  short: '',
  size: 13,
  rdesc: '[Names of the alpha channels]' }
Resource:  { at: 14872,
  type: '8BIM',
  id: 1045,
  namelen: 0,
  name: '',
  short: '',
  size: 30,
  rdesc: '[Unicode Alpha Names]' }
Resource:  { at: 14914,
  type: '8BIM',
  id: 1007,
  namelen: 0,
  name: '',
  short: '',
  size: 14,
  rdesc: '[DisplayInfo]' }
Resource:  { at: 14940,
  type: '8BIM',
  id: 1077,
  namelen: 0,
  name: '',
  short: '',
  size: 17,
  rdesc: '[undefined]' }
Resource:  { at: 14970,
  type: '8BIM',
  id: 1053,
  namelen: 0,
  name: '',
  short: '',
  size: 4,
  rdesc: '[Alpha Identifiers]' }
Resource:  { at: 14986,
  type: '8BIM',
  id: 1037,
  namelen: 0,
  name: '',
  short: '',
  size: 4,
  rdesc: '[Global Angle]' }
Resource:  { at: 15002,
  type: '8BIM',
  id: 1049,
  namelen: 0,
  name: '',
  short: '',
  size: 4,
  rdesc: '[Global Altitude]' }
Resource:  { at: 15018,
  type: '8BIM',
  id: 1011,
  namelen: 0,
  name: '',
  short: '',
  size: 9,
  rdesc: '[Print flags]' }
Resource:  { at: 15040,
  type: '8BIM',
  id: 10000,
  namelen: 0,
  name: '',
  short: '',
  size: 10,
  rdesc: '[Print flags info]' }
Resource:  { at: 15062,
  type: '8BIM',
  id: 1013,
  namelen: 0,
  name: '',
  short: '',
  size: 72,
  rdesc: '[Color halftoning info]' }
Resource:  { at: 15146,
  type: '8BIM',
  id: 1016,
  namelen: 0,
  name: '',
  short: '',
  size: 112,
  rdesc: '[Color transfer functions]' }
Resource:  { at: 15270,
  type: '8BIM',
  id: 1024,
  namelen: 0,
  name: '',
  short: '',
  size: 2,
  rdesc: '[Layer state info]' }
Resource:  { at: 15284,
  type: '8BIM',
  id: 1026,
  namelen: 0,
  name: '',
  short: '',
  size: 2,
  rdesc: '[Layers group info]' }
Resource:  { at: 15298,
  type: '8BIM',
  id: 1072,
  namelen: 0,
  name: '',
  short: '',
  size: 1,
  rdesc: '[undefined]' }
Resource:  { at: 15312,
  type: '8BIM',
  id: 1069,
  namelen: 0,
  name: '',
  short: '',
  size: 6,
  rdesc: '[undefined]' }
Resource:  { at: 15330,
  type: '8BIM',
  id: 1032,
  namelen: 0,
  name: '',
  short: '',
  size: 16,
  rdesc: '[Grid and guides info]' }
Resource:  { at: 15358,
  type: '8BIM',
  id: 1078,
  namelen: 0,
  name: '',
  short: '',
  size: 168,
  rdesc: '[undefined]' }
Resource:  { at: 15538,
  type: '8BIM',
  id: 1075,
  namelen: 0,
  name: '',
  short: '',
  size: 516,
  rdesc: '[undefined]' }
Resource:  { at: 16066,
  type: '8BIM',
  id: 1076,
  namelen: 0,
  name: '',
  short: '',
  size: 70,
  rdesc: '[undefined]' }
Resource:  { at: 16148,
  type: '8BIM',
  id: 1054,
  namelen: 0,
  name: '',
  short: '',
  size: 4,
  rdesc: '[URL List]' }
Resource:  { at: 16164,
  type: '8BIM',
  id: 1050,
  namelen: 0,
  name: '',
  short: '',
  size: 841,
  rdesc: '[Slices]' }
Resource:  { at: 17018,
  type: '8BIM',
  id: 1064,
  namelen: 0,
  name: '',
  short: '',
  size: 12,
  rdesc: '[undefined]' }
Resource:  { at: 17042,
  type: '8BIM',
  id: 1039,
  namelen: 0,
  name: '',
  short: '',
  size: 3144,
  rdesc: '[ICC Profile]' }
Resource:  { at: 20198,
  type: '8BIM',
  id: 1044,
  namelen: 0,
  name: '',
  short: '',
  size: 4,
  rdesc: '[Document specific IDs]' }
Resource:  { at: 20214,
  type: '8BIM',
  id: 1036,
  namelen: 0,
  name: '',
  short: '',
  size: 1257,
  rdesc: '[Thumbnail resource]' }
Resource:  { at: 21484,
  type: '8BIM',
  id: 1057,
  namelen: 0,
  name: '',
  short: '',
  size: 85,
  rdesc: '[Version Info]' }
Resource:  { at: 21582,
  type: '8BIM',
  id: 1058,
  namelen: 0,
  name: '',
  short: '',
  size: 302,
  rdesc: '[undefined]' }
Resource:  { at: 21896,
  type: '8BIM',
  id: 4000,
  namelen: 0,
  name: '',
  short: '',
  size: 264,
  rdesc: '[undefined]' }
Resource:  { at: 22172,
  type: '8BIM',
  id: 4001,
  namelen: 0,
  name: '',
  short: '',
  size: 28,
  rdesc: '[undefined]' }

### Layers & Masks ###
Layer info for 1:
Layer 0: { idx: 0,
  top: 24,
  left: 52,
  bottom: 71,
  right: 101,
  channels: 4,
  rows: 47,
  cols: 49 }
Channel 0: id=-1, 370 bytes
Channel 1: id=0, 190 bytes
Channel 2: id=1, 190 bytes
Channel 3: id=2, 190 bytes
Blending mode: { sig: '8BIM',
  key: 'norm',
  opacity: 255,
  clipping: 0,
  flags: 24,
  filler: 0,
  opacp: 100.49803921568628,
  blending: 'normal' }
Skipped layer blending ranges with 40 bytes
Layer name: Shape 1
# Image: Shape 1/4
Handling RLE compressed data
currentpos: 23020 should be 23294
Handling RLE compressed data
currentpos: 23390 should be 23484
Handling RLE compressed data
currentpos: 23580 should be 23674
Handling RLE compressed data
currentpos: 23770 should be 23864
RGBA [ null, null, null, null ]
Skipped 40 bytes at end of misc data?
# Image: merged/4
Handling RLE compressed data
ERROR: Unsupported number of channels