address some additional compiler warnings

SignalMessaging/utils/DebugLogger.m

@@ -106,7 +106,7 @@
     // This should be redundant with the logic above.
     [logPathSet addObjectsFromArray:self.fileLogger.logFileManager.unsortedLogFilePaths];
     NSArray<NSString *> *logPaths = logPathSet.allObjects;
-    return [logPaths sortedArrayUsingSelector:@selector(compare:)];
+    return [logPaths sortedArrayUsingSelector:@selector((compare:))];
 }
 
 - (void)wipeLogs

SignalServiceKit/src/Util/MIMETypeUtil.m

@@ -320,8 +320,6 @@ NSString *const kSyncMessageFileExtension = @"bin";
             // Store the file in a subdirectory whose name is the uniqueId of this attachment,
             // to avoid collisions between multiple attachments with the same name.
             NSString *attachmentFolderPath = [folder stringByAppendingPathComponent:uniqueId];
-            NSError *error = nil;
-            BOOL attachmentFolderPathExists = [[NSFileManager defaultManager] fileExistsAtPath:attachmentFolderPath];
             if (![OWSFileSystem ensureDirectoryExists:attachmentFolderPath]) {
                 return nil;
             }