Angular Js Errors are not understandable - angularjs

Question

I am unable to understand the errors of Angular JS. I am trying to build a factory but it keeps on giving me the following error in firefox console.
Error: [ng:areq] http://errors.angularjs.org/1.2.9/ng/areq?p0=hospitalController&p1=not%20a%20function%2C%20got%20undefined
My Code is
index
<div class="main ng-scope" ng-view="">
partial
<button data-ng-click="ShowStaff()">show</button>
app.js
var myApp = angular.module('myApp', [
'ngRoute',
'artistControllers'
]);
myApp.config(['$routeProvider', function($routeProvider) {
$routeProvider.
when('/list', {
templateUrl: 'partials/list.html',
controller: 'ListController'
}).
when('/hospital', {
templateUrl: 'partials/hospital.html',
controller: 'hospitalController'
}).
when('/docter', {
templateUrl: 'partials/docters.html',
controller: 'docterController'
}).
when('/details/:itemId', {
templateUrl: 'partials/details.html',
controller: 'DetailsController'
}).
otherwise({
redirectTo: '/hospital'
});
}]);
controller.js
var artistControllers = angular.module('artistControllers', ['ngAnimate']);
artistControllers.controller('ListController', ['$scope', '$http', function($scope, $http) {
$http.get('js/data.json').success(function(data) {
$scope.artists = data;
$scope.artistOrder = 'name';
});
// Starting Factory for Doctor and hospital relationship
artistControllers.factory( 'StaffFactory','$http',function(){
var factory = {};
$http.get('js/hospital.json').success(function(data) {
factory.hospitals = data;
//$scope.hospitalOrder = 'name';
});
$http.get('js/docters.json').success(function(data) {
factory.doctors = data;
//$scope.hospitalOrder = 'name';
});
factory.getDocs = function(){
return factory.doctors;
};
factory.getHos= function(){
return factory.hospitals;
};
factory.getStaff = function(){
var result=[];
var endres=[];
angular.forEach(factory.hospitals, function(hospital){
result=[];
angular.forEach(factory.doctors,function(doc){
if(doc.id==hospital.id)
{
result.push(doc);
}
});
endres.push([hospital,result]);
});
return endres;
}
return factory;
});
artistControllers.SimpleController=function($scope,StaffFactory){
$scope.customers=[];
$scope.hospitals=[ ];
$scope.doctors=[];
$scope.staff=[];
init();
function init()
{
$scope.doctors=StaffFactory.getDocs();
$scope.hospitals=StaffFactory.getHos();
}
$scope.ShowStaff = function()
{
$scope.staff=StaffFactory.getStaff();
}
};
// Ending Factory for Doctor and hospital relationship
}]);

Answer 1

In addition to the actual error explained by #dave, if you want eror messages to be more explicit without having to follow a link, you should use angular.js instead of angular.min.js (the minimized one) for your development environment.

Answer 2

If you follow the link in the error, you will see
Argument 'hospitalController' is not a function, got undefined
It sounds like you have in your html somewhere:
ng-controller="hospitalController"
but you haven't created a controller with that name.