fix(sync): fix synchronous completion

nah... mukla like to hide some tests some times - no errors, no completion and even not shown...

index.js

@@ -68,15 +68,16 @@ function tryCatch (fn, opts, cb) {
   if (typeof cb !== 'function') {
     throw new TypeError('try-catch-core: expect `cb` to be a function')
   }
-  cb = utils.isAsync(fn)
+  var isAsyncFn = utils.isAsync(fn)
+  cb = isAsyncFn
     ? utils.once(utils.dezalgo(cb))
     : utils.once(cb)
   opts = opts && typeof opts === 'object'
     ? opts
     : {}
   opts.passCallback = typeof opts.passCallback === 'boolean'
     ? opts.passCallback
-    : true
+    : isAsyncFn // if `fn` is async, pass callback automatically
 
   utils.tryCatchCallback.call(this, fn, opts, cb)
 }

test.js

@@ -94,6 +94,16 @@ test('should pass result from `fs.readFile` to the callback', function (done) {
   })
 })
 
+test('should get result of `fs.readFileSync`', function (done) {
+  tryCatchCore(function () {
+    return fs.readFileSync('./README.md', 'utf8')
+  }, function (err, res) {
+    test.strictEqual(err, null)
+    test.strictEqual(res.indexOf('try-catch-core') !== -1, true)
+    done()
+  })
+})
+
 test('should be able to pass custom arguments through options', function (done) {
   tryCatchCore(function (foo, bar, next) {
     test.strictEqual(arguments.length, 3)