Improve errors in TwoMBit.

Author: clobber

SMSGameCore.mm

@@ -301,7 +301,15 @@ - (void)saveStateToFileAtPath:(NSString *)fileName completionHandler:(void (^)(B
     int saveStateSize = smsSavestateSize();
     NSMutableData *stateData = [NSMutableData dataWithLength:saveStateSize];
 
-    smsSaveState((unsigned char *)[stateData mutableBytes], saveStateSize);
+    if(!smsSaveState((unsigned char *)[stateData mutableBytes], saveStateSize))
+    {
+        NSError *error = [NSError errorWithDomain:OEGameCoreErrorDomain code:OEGameCoreCouldNotSaveStateError userInfo:@{
+            NSLocalizedDescriptionKey : @"Save state data could not be written",
+            NSLocalizedRecoverySuggestionErrorKey : @"The emulator could not write the state data."
+        }];
+        block(NO, error);
+        return;
+    }
 
     __autoreleasing NSError *error = nil;
     BOOL success = [stateData writeToFile:fileName options:NSDataWritingAtomic error:&error];
@@ -323,17 +331,20 @@ - (void)loadStateFromFileAtPath:(NSString *)fileName completionHandler:(void (^)
     int saveStateSize = smsSavestateSize();
     if(saveStateSize != [data length])
     {
-        // FIXME: Provide constants for error handling in OpenEmu SDK.
-        NSError *error = [NSError errorWithDomain:@"org.openemu.GameCore.Load" code:-10 userInfo:
-                          @{ NSLocalizedDescriptionKey : [NSString stringWithFormat:@"The size of the file %@ does not have the right size, %d expected, got: %ld.", fileName, saveStateSize, [data length]] }];
+        NSError *error = [NSError errorWithDomain:OEGameCoreErrorDomain code:OEGameCoreStateHasWrongSizeError userInfo:@{
+            NSLocalizedDescriptionKey : @"Save state has wrong file size.",
+            NSLocalizedRecoverySuggestionErrorKey : [NSString stringWithFormat:@"The size of the file %@ does not have the right size, %d expected, got: %ld.", fileName, saveStateSize, [data length]],
+        }];
         block(NO, error);
         return;
     }
 
     if(!smsLoadState((unsigned char *)[data bytes], saveStateSize))
     {
-        NSError *error = [NSError errorWithDomain:@"org.openemu.GameCore.Load" code:-10 userInfo:
-                          @{ NSLocalizedDescriptionKey : [NSString stringWithFormat:@"Could not read the file state in %@.", fileName] }];
+        NSError *error = [NSError errorWithDomain:OEGameCoreErrorDomain code:OEGameCoreCouldNotLoadStateError userInfo:@{
+            NSLocalizedDescriptionKey : @"The save state data could not be read",
+            NSLocalizedRecoverySuggestionErrorKey : [NSString stringWithFormat:@"Could not read the file state in %@.", fileName]
+        }];
         block(NO, error);
         return;
     }