AngularJS Error: [$controller:ctrlreg] Controller is not registered - ruby-on-rails

Question

StackOverflow Peeps,
I'm having a bit of an issue with the error referenced in the title. I've scoured AngularJS documentation, previously written code, and existing StackOverflow question/answers, all to no avail. To start, here is a previously written Angular controller that works correctly:
Correct, functioning controller
And here is the malfunctioning controller:
Malfunctioning controller
What is particularly frustrating is that I quite literally copied my code from the functioning Angular controller ("focus_groups_ctrl") into my new controller ("agencies_ctrl"), and simply updated the variable/argument names to reflect this. What am I missing here? The JSON data being rendered in api/v1/agencies is working correctly, and my HTML page is being correctly "wrapped" in ng-app and ng-controller attributes. Please let me know, and feel free to ask away! Thanks!
Here is the malfunctioning code:
/* global angular */
(function() {
"use strict";
angular.module("app", ["ngAnimate"]).controller("agencies_Ctrl", function($scope, $http) {
$scope.setup = function() {
$http.get('/api/v1/agencies' + window.location.search).then(function(response) {
$scope.agenciesOffset = 0;
$scope.agenciesCount = 5;
$scope.agencies = response.data;
console.log($scope.agencies);
});
};
var i = 5;
$scope.nextLoad = function() {
$scope.agenciesOffset = i;
i += 5;
};
});
}());
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
And here is the functioning code:
/* global angular */
(function() {
"use strict";
angular.module("app", ["ngAnimate"]).controller("focus_groups_Ctrl", function($scope, $http) {
$scope.setup = function() {
$http.get('/api/v1/focus-groups' + window.location.search).then(function(response) {
$scope.focusGroupOffset = 0;
$scope.focusGroupCount = 5;
$scope.focusGroups = response.data;
console.log($scope.focusGroups);
});
};
var i = 5;
$scope.nextLoad = function() {
$scope.focusGroupOffset = i;
i += 5;
};
});
}());
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>

Answer 1

An unknown controller error can also be caused by accidentally redefining a module using the angular.module API, as shown in the following example.
angular.module("app", ["ngAnimate"]).controller("agencies_Ctrl", fn1);
angular.module("app", ["ngAnimate"]).controller("focus_groups_Ctrl", fn2);
To fix this problem, make sure you only define each module with the angular.module(name, [requires]) syntax once across your entire project. Retrieve it for subsequent use with angular.module(name). The fixed example is shown below.
angular.module("app", ["ngAnimate"]);
angular.module("app").controller("agencies_Ctrl", fn1);
angular.module("app").controller("focus_groups_Ctrl", fn2);