added stdout check to exec

app.js

@@ -49,10 +49,9 @@
 	};
 
 	require('child_process').exec('/usr/bin/which convert', function(err, stdout, stderr) {
-		if(err) {
+		if(err || !stdout) {
-			winston.warn('Counldn\'t find convert. Did you install imagemagick? ', err.message);
+			winston.warn('Counldn\'t find convert. Did you install imagemagick?');
 		}
-		winston.warn('Counldn\'t find convert. Did you install imagemagick? ', err);
 	});
 
 	// Log GNU copyright info along with server info