Added error checking to the sample project.

Author: nfarina

SMXMLDocument.m

@@ -166,6 +166,8 @@ - (id)initWithData:(NSData *)data error:(NSError **)outError {
 			[self release];
 			return nil;
 		}
+        else if (outError)
+            *outError = nil;
 	}
 	return self;
 }

XMLDocumentSamples/AppDelegate.m

@@ -10,8 +10,15 @@ - (void) applicationDidFinishLaunching:(UIApplication *)application {
 	NSData *data = [NSData dataWithContentsOfFile:sampleXML];
 
 	// create a new SMXMLDocument with the contents of sample.xml
-	SMXMLDocument *document = [SMXMLDocument documentWithData:data error:NULL];
+    NSError *error;
+	SMXMLDocument *document = [SMXMLDocument documentWithData:data error:&error];
 
+    // check for errors
+    if (error) {
+        NSLog(@"Error while parsing the document: %@", error);
+        return;
+    }
+    
 	// demonstrate -description of document/element classes
 	NSLog(@"Document:\n %@", document);