Another nice one: Accidentally redefining modules. I copy/pasted stuff a little too eagerly earlier today and ended up having a module definition somewhere, that I overrode with my controller definitions:
// controllers.js - dependencies in one place, perfectly fine
angular.module('my.controllers', [/* dependencies */]);
Then in my definitions, I was supposed to reference it like so:
// SomeCtrl.js - grab the module, add the controller
angular.module('my.controllers')
.controller('SomeCtrl', function() { /* ... */ });
What I did instead, was:
// Do not try this at home!
// SomeCtrl.js
angular.module('my.controllers', []) // <-- redefined module, no harm done yet
.controller('SomeCtrl', function() { /* ... */ });
// SomeOtherCtrl.js
angular.module('my.controllers', []) // <-- redefined module - SomeCtrl no longer accessible
.controller('SomeOtherCtrl', function() { /* ... */ });
Note the extra bracket in the call to angular.module.