Merge pull request Mantle#661 from kypselia/improved_error

Improved error descriptions

Mantle/MTLJSONAdapter.h

@@ -90,6 +90,12 @@ extern const NSInteger MTLJSONAdapterErrorInvalidJSONDictionary;
 /// does not actually exist in +propertyKeys.
 extern const NSInteger MTLJSONAdapterErrorInvalidJSONMapping;
 
+/// An exception was thrown and caught.
+extern const NSInteger MTLJSONAdapterErrorExceptionThrown;
+
+/// Associated with the NSException that was caught.
+extern NSString * const MTLJSONAdapterThrownExceptionErrorKey;
+
 /// Converts a MTLModel object to and from a JSON dictionary.
 @interface MTLJSONAdapter : NSObject
 

Mantle/MTLJSONAdapter.m

@@ -28,7 +28,7 @@
 const NSInteger MTLJSONAdapterErrorExceptionThrown = 1;
 
 // Associated with the NSException that was caught.
-static NSString * const MTLJSONAdapterThrownExceptionErrorKey = @"MTLJSONAdapterThrownException";
+NSString * const MTLJSONAdapterThrownExceptionErrorKey = @"MTLJSONAdapterThrownException";
 
 @interface MTLJSONAdapter ()
 
@@ -343,7 +343,8 @@ - (id)modelFromJSONDictionary:(NSDictionary *)JSONDictionary error:(NSError **)e
 			#else
 			if (error != NULL) {
 				NSDictionary *userInfo = @{
-					NSLocalizedDescriptionKey: ex.description,
+					NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Caught exception parsing JSON key path \"%@\" for model class: %@", JSONKeyPaths, self.modelClass],
+					NSLocalizedRecoverySuggestionErrorKey: ex.description,
 					NSLocalizedFailureReasonErrorKey: ex.reason,
 					MTLJSONAdapterThrownExceptionErrorKey: ex
 				};