assert: fix throws() throws an error without message property

Fixes #2893.

lib/assert.js

@@ -306,11 +306,11 @@ function _throws(shouldThrow, block, expected, message) {
             (message ? ' ' + message : '.');
 
   if (shouldThrow && !actual) {
-    fail('Missing expected exception' + message);
+    fail(actual, expected, 'Missing expected exception' + message);
   }
 
   if (!shouldThrow && expectedException(actual, expected)) {
-    fail('Got unwanted exception' + message);
+    fail(actual, expected, 'Got unwanted exception' + message);
   }
 
   if ((shouldThrow && actual && expected &&

test/simple/test-assert.js

@@ -283,3 +283,13 @@ testAssertionMessage({a: undefined, b: null}, '{"a":"undefined","b":null}');
 testAssertionMessage({a: NaN, b: Infinity, c: -Infinity},
     '{"a":"NaN","b":"Infinity","c":"-Infinity"}');
 
+// #2893
+try {
+  assert.throws(function () {
+    assert.ifError(null);
+  });
+} catch (e) {
+  threw = true;
+  assert.equal(e.message, 'Missing expected exception..');
+}
+assert.ok(threw);