Fix case that user can be undefined

Author: Theresa

app/views/comments/comments_all.html.erb

@@ -16,7 +16,9 @@
       <tr>
         <td><%= link_to comment.exercise.title, exercise_path(comment.exercise) %></td>
         <td><%= comment.text %></td>
-        <% if comment.user.first_name.nil? %>
+        <% if !comment.user %>
+           <td> <%= 'User undefined' %> </td>
+        <% elsif comment.user.first_name.nil?%>
             <td><%= link_to "User#{comment.user.id}", user_path(comment.user)%></td>
         <% else %>
             <td><%= link_to comment.user.name, user_path(comment.user) %></td>

app/views/comments/index.html.erb

@@ -25,10 +25,12 @@
       <% @comments.each do |comment| %>
         <tr>
           <td><%= comment.text %></td>
-          <% if comment.user.first_name.nil? %>
-            <td><%= "User#{comment.user.id}"%></td>
+          <% if !comment.user %>
+             <td> <%= 'User undefined' %> </td>
+          <% elsif comment.user.first_name.nil?%>
+              <td><%=  "User#{comment.user.id}"%></td>
           <% else %>
-            <td><%= comment.user.name %></td>
+              <td><%= comment.user.name%></td>
           <% end %>
           <td><%= comment.created_at %>
           <td><div class="actions btn-group" role="group">

app/views/exercises/exercises_all.html.erb

@@ -16,7 +16,7 @@
       <tr>
         <td><%= link_to exercise.title, exercise %></td>
         <% if !exercise.user %>
-            <%= 'User undefined' %>
+            <td> <%= 'User undefined' %> </td>
         <% elsif exercise.user.first_name.nil?%>
             <td><%= link_to "User#{exercise.user.id}", user_path(exercise.user)%></td>
         <% else %>

app/views/exercises/show.html.erb

@@ -14,14 +14,12 @@
   <dt><%= 'Visibility' %>:</dt>
   <dd><%= @exercise.public ? 'public' : 'private' %></dd>
   <dt><%= 'Created by' %>:</dt>
-  <% if @exercise.user %>
-    <% if @exercise.user.first_name.nil?%>
+  <% if !@exercise.user %>
+      <dd><%= 'User undefined' %></dd>
+  <% elsif @exercise.user.first_name.nil?%>
       <dd><%= "User#{@exercise.user.id}"%></dd>
-    <% else %>
-      <dd><%= @exercise.user.name %></dd>
-    <% end %>
   <% else %>
-    <dd><%= 'User undefined' %></dd>
+      <dd><%= @exercise.user.name %></dd>
   <% end %>
   <dt><%= 'Created at' %>:</dt>
   <dd><%= @exercise.created_at %></dd>