Bug Fix: Add some safety checks to URL handlers

A few places could have used nil checks, but there shouldn't be anything
passing nil URLs to these. Well, just in case, at least it won't lead to
crashes or something...

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Application/AppController.m

@@ -234,8 +234,15 @@ static BOOL consentLastEnabled = NO;
 			[playlistLoader addDatabase];
 		} else if([[NSFileManager defaultManager] fileExistsAtPath:[basePath stringByAppendingPathComponent:newFilename]]) {
 			[playlistLoader addURL:[NSURL fileURLWithPath:[basePath stringByAppendingPathComponent:newFilename]]];
-		} else {
+		} else if([[NSFileManager defaultManager] fileExistsAtPath:[basePath stringByAppendingPathComponent:oldFilename]]){
+			/* Without the above check, it appears the code was retrieving a nil NSURL from the nonexistent path
+			 * Then adding it to the playlist and crashing further down the line
+			 * Nobody on a new setup should be seeing this open anything, so it should fall through to the
+			 * notice below.
+			 */
 			[playlistLoader addURL:[NSURL fileURLWithPath:[basePath stringByAppendingPathComponent:oldFilename]]];
+		} else {
+			ALog(@"No playlist found, leaving it empty.");
 		}
 	}
 

Audio/Chain/BufferChain.m

@@ -52,10 +52,14 @@
 }
 
 - (BOOL)open:(NSURL *)url withOutputFormat:(AudioStreamBasicDescription)outputFormat withUserInfo:(id)userInfo withRGInfo:(NSDictionary *)rgi {
+	if(!url) {
+		DLog(@"Player attempted to play invalid file...");
+		return NO;
+	}
 	[self setStreamURL:url];
 	[self setUserInfo:userInfo];
 
-	if (![self buildChain]) {
+	if(![self buildChain]) {
 		DLog(@"Couldn't build processing chain...");
 		return NO;
 	}

Playlist/PlaylistLoader.m

@@ -1112,6 +1112,7 @@ NSURL *_Nullable urlForPath(NSString *_Nullable path);
 }
 
 - (NSArray *)addURL:(NSURL *)url {
+	if(!url) return [NSArray array];
 	return [self insertURLs:@[url] atIndex:(int)[[playlistController content] count] sort:NO];
 }
 

Utils/SandboxBroker.m

@@ -420,6 +420,7 @@ static inline void dispatch_async_reentrant(dispatch_queue_t queue, dispatch_blo
 }
 
 - (const void *)beginFolderAccess:(NSURL *)fileUrl {
+	if(!fileUrl) return NULL;
 	NSURL *folderUrl = [SandboxBroker urlWithoutFragment:fileUrl];
 	if(![folderUrl isFileURL]) return NULL;