Add edge cases

Author: Theresa

app/views/carts/index.html.erb

@@ -9,7 +9,9 @@
       <% if cart.user === current_user %>
         <% if cart.exercises %>
           <% cart.exercises.each do |exercise| %>
-            <dd><%= link_to exercise.title, exercise_path(exercise) %></dd>
+            <% if exercise %>
+              <dd><%= link_to exercise.title, exercise_path(exercise) %></dd>
+            <% end %>
           <% end %>
         <% else%>
           <dd> <%= 'No exercises added' %></dd>

app/views/collections/index.html.erb

@@ -18,7 +18,9 @@
           <td><%= collection.title %></td>
           <% if collection.exercises %>
             <% collection.exercises.each do |exercise| %>
-              <td><%= link_to exercise.title, exercise_path(exercise) %></td>
+              <%if exercise%>
+                <td><%= link_to exercise.title, exercise_path(exercise) %></td>
+              <% end %>
             <% end %>
           <% else%>
             <td> <%= 'No exercises added' %></td>