Prevent EXC_BAD_ACCESS crash by null-checking proper error

[ericbomgardner]

Problem

If writing a screenshot fails due to failure to create a directory, an error is assigned to the error parameter. However, when writeScreenShotForLine:... is called with a NULL error param by writeScreenshotForException: in XCTestCase-KIFAdditions.m, the assignment causes a crash with EXC_BAD_ACCESS.

Relevant excerpt from XCTestCase-KIFAdditions.m:

KIF/Additions/XCTestCase-KIFAdditions.m

Line 67 in 0ea470b

[[UIApplication sharedApplication] writeScreenshotForLine:[exception.userInfo[@"LineNumberKey"] unsignedIntegerValue] inFile:exception.userInfo[@"FilenameKey"] description:nil error:NULL];

This regression was introduced by commit f4705fb (#981), which changed the error checked by the if (error) { ... } check away from error.

Fix

Revert f4705fb -- check proper error again.

This parallels all the other if (error) checks in writeScreenShotForLine:....

QA Plan

• Confirm that crash no longer occurs when writing a screenshot fails due to failure to create a directory
• Confirm that behavior is acceptable when directoryCreationError is nil:
  • When simulating a nil directoryCreationError, result of printing error: Error Domain=KIFTest Code=0 "Couldn't create directory at path $CIRCLE_ARTIFACTS (details: (null))" UserInfo={NSLocalizedDescription=Couldn't create directory at path $CIRCLE_ARTIFACTS (details: (null))}

[justinseanmartin]

Thanks for the contribution!