Merge pull request #322 from LeeHoward1/guessfix

Checking for undefined Intl.DateTimeFormat().resolvedOptions().timeZone

moment-timezone.js

@@ -325,11 +325,13 @@
 		// use Intl API when available and returning valid time zone
 		try {
 			var intlName = Intl.DateTimeFormat().resolvedOptions().timeZone;
-			var name = names[normalizeName(intlName)];
-			if (name) {
-				return name;
+			if (intlName){
+				var name = names[normalizeName(intlName)];
+				if (name) {
+					return name;
+				}
+				logError("Moment Timezone found " + intlName + " from the Intl api, but did not have that data loaded.");
 			}
-			logError("Moment Timezone found " + intlName + " from the Intl api, but did not have that data loaded.");
 		} catch (e) {
 			// Intl unavailable, fall back to manual guessing.
 		}

tests/moment-timezone/guess.js

@@ -89,6 +89,22 @@ exports.guess = {
 		test.done();
 	},
 
+	"When Intl is available, but timeZone is undefined, should return a guess without logging an error" : function (test) {
+		var oldError = console.error;
+		var errors = '';
+		console.error = function (message) {
+			errors += message;
+		};
+
+		mockIntlTimeZone(undefined);
+		mockTimezoneOffset(tz.zone('Europe/London'));
+		test.equal(tz.guess(true), 'Europe/London');
+		test.equal(errors, '');
+
+		console.error = oldError;
+		test.done();
+	},
+
 	"ensure each zone is represented" : function (test) {
 		var names = tz.names();
 		var zone, i;