No error checking for missing .tif file

[enlarsen]

If the properly named .tif file isn't in the same directory, program keeps running but:

Jul 2 08:07:15 iMac Tesseract Box Editor[9552] : CGContextDrawImage: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
2014-07-02 08:07:15.169 Tesseract Box Editor[9552:303] Cannot lock focus on image <NSImage 0x600000663e80 Size={0, 0} Reps=(
)>, because it is size zero.
2014-07-02 08:07:15.276 Tesseract Box Editor[9552:303](0 CoreFoundation 0x00007fff8a86225c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff90bcce75 objc_exception_throw + 43
2 CoreFoundation 0x00007fff8a86210c +[NSException raise:format:] + 204
3 AppKit 0x00007fff89215f69 -[NSImage _lockFocusOnRepresentation:rect:context:hints:flipped:] + 334
4 AppKit 0x00007fff89215e09 __51-[NSImage lockFocusWithRect:context:hints:flipped:]_block_invoke + 82
5 AppKit 0x00007fff89215266 -[NSImage _usingBestRepresentationForRect:context:hints:body:] + 170
6 AppKit 0x00007fff892151a7 -[NSImage lockFocusWithRect:context:hints:flipped:] + 207
7 AppKit 0x00007fff89398844 -[NSImage lockFocusFlipped:] + 123
8 Tesseract Box Editor 0x00000001000133b4 TFC18TesseractBoxEditor26ImageViewWithSelectionRect9trimImagefS0_FCSo7NSImageT + 4324
9 Tesseract Box Editor 0x00000001000136a2 TToFC18TesseractBoxEditor26ImageViewWithSelectionRect9trimImagefS0_FCSo7NSImageT + 66
10 Tesseract Box Editor 0x000000010002238f TFC18TesseractBoxEditor24DocumentWindowController13windowDidLoadfS0_FT_T + 3695
11 Tesseract Box Editor 0x0000000100022ce2 TToFC18TesseractBoxEditor24DocumentWindowController13windowDidLoadfS0_FT_T + 34
12 AppKit 0x00007fff893af3ac -[NSWindowController _windowDidLoad] + 450
13 AppKit 0x00007fff89395fa6 -[NSWindowController window] + 110
14 AppKit 0x00007fff893970f0 -[NSWindowController showWindow:] + 36
15 AppKit 0x00007fff894635f5 -[NSDocument showWindows] + 100
16 AppKit 0x00007fff895c982d __80-[NSDocumentController openDocumentWithContentsOfURL:display:completionHandler:]_block_invoke855 + 198
17 AppKit 0x00007fff895c9416 __80-[NSDocumentController openDocumentWithContentsOfURL:display:completionHandler:]_block_invoke837 + 237
18 AppKit 0x00007fff895c8e31 __80-[NSDocumentController openDocumentWithContentsOfURL:display:completionHandler:]_block_invoke_4 + 578
19 AppKit 0x00007fff895c8120 -[NSDocumentController _openDocumentWithContentsOfURL:usingProcedure:] + 583
20 AppKit 0x00007fff895c8bcb __80-[NSDocumentController openDocumentWithContentsOfURL:display:completionHandler:]_block_invoke_3 + 300
21 CoreFoundation 0x00007fff8a79348c CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK + 12
22 CoreFoundation 0x00007fff8a784ae5 __CFRunLoopDoBlocks + 341
23 CoreFoundation 0x00007fff8a7843de __CFRunLoopRun + 814
24 CoreFoundation 0x00007fff8a783e75 CFRunLoopRunSpecific + 309
25 HIToolbox 0x00007fff88d07a0d RunCurrentEventLoopInMode + 226
26 HIToolbox 0x00007fff88d07685 ReceiveNextEventCommon + 173
27 HIToolbox 0x00007fff88d075bc _BlockUntilNextEventMatchingListInModeWithFilter + 65
28 AppKit 0x00007fff8911a24e _DPSNextEvent + 1434
29 AppKit 0x00007fff8911989b -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
30 AppKit 0x00007fff8910d99c -[NSApplication run] + 553
31 AppKit 0x00007fff890f8783 NSApplicationMain + 940
32 Tesseract Box Editor 0x000000010002a4f2 main + 34
33 libdyld.dylib 0x00007fff8ef565fd start + 1
34 ??? 0x0000000000000003 0x0 + 3)