Remove unnused code

Author: stig

src/test/objc/ErrorTest.m

@@ -48,10 +48,6 @@ - (void)setUp {
     writer = [SBJsonWriter new];
 }
 
-- (NSString*)otherFileName {
-    return @"error";
-}
-
 - (void)testNonStringDictionaryKey {
     NSArray *keys = [NSArray arrayWithObjects:[NSNull null],
                      [NSNumber numberWithInt:1],