Getting error "Failed: Fn is not a function" when try to automate e2e for a login page - protractor

Question

I am trying to automate and rum a simple register form but i am getting error saying "Failed: Fn is not a function". Below is my code
describe('Locator testing by model', function(){
it('automate user register form', function(){
browser.get('http://www.way2automation.com/angularjs-protractor/registeration/#/login');
element(by.model('Auth.user.name')).sendKeys('angular');
element(by.model('Auth.user.password')).sendKeys('password');
element(by.model('model[options.key]')).sendKeys('zafaque');
element(by.buttonText('Login')).click();
browser.wait(3000);
});
});
below is the error detail
1) Locator testing by model automate user register form
Message:
Failed: fn is not a function
Stack:
TypeError: fn is not a function
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/webdriver.js:716:14
at TaskQueue.execute_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2913:14)
at TaskQueue.executeNext_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2896:21)
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2820:25
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:639:7
at process._tickCallback (node.js:369:9)
From: Task: <anonymous>
at pollCondition (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2359:16)
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2355:9
at new ManagedPromise (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:1082:7)
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2354:14
at TaskQueue.execute_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2913:14)
at TaskQueue.executeNext_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2896:21)
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2775:27
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:639:7
at process._tickCallback (node.js:369:9)
From: Task: <anonymous wait>
at ControlFlow.wait (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2352:17)
at Driver.wait (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/webdriver.js:712:29)
at ProtractorBrowser.to.(anonymous function) [as wait] (/usr/local/lib/node_modules/protractor/built/browser.js:60:29)
at Object.<anonymous> (/Users/zafaque/WebstormProjects/autotation/udemyProject/loginTest.js:12:17)
at /usr/local/lib/node_modules/protractor/node_modules/jasminewd2/index.js:94:23
at new ManagedPromise (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:1082:7)
at controlFlowExecute (/usr/local/lib/node_modules/protractor/node_modules/jasminewd2/index.js:80:18)
at TaskQueue.execute_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2913:14)
at TaskQueue.executeNext_ (/usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2896:21)
at /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2820:25
From: Task: Run it("automate user register form") in control flow
at Object.<anonymous> (/usr/local/lib/node_modules/protractor/node_modules/jasminewd2/index.js:79:14)
From asynchronous test:
Error
at Suite.<anonymous> (/Users/zafaque/WebstormProjects/autotation/udemyProject/loginTest.js:6:5)
at Object.<anonymous> (/Users/zafaque/WebstormProjects/autotation/udemyProject/loginTest.js:4:1)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)

Answer 1

You are using browser.wait() incorrectly. Refer the official documentation for correct usage here
browser.wait() accepts params in the below order
first argument is a condition which can be a function or a
webdriver.promise.Promise or a Expected Condition Second Argument is
the timeout
But you are passing timeout as the first argument. Incase you just wait a conditionless wait - Just use browser.sleep(3000)