app: Add ParameterMissing exception handling

This way, if a parameter is missing in a request, it is logged as a
400 Bad Request instead of a 500 Internal Server Error.

Author: awilfox

app/controllers/concerns/exception_handling.rb

@@ -29,6 +29,11 @@ def log_error(error)
       render :not_found, status: :not_found, locals: { exception: error }
     end
 
+    rescue_from ActionController::ParameterMissing do |error|
+      log_error(error)
+      render :bad_request, status: :bad_request, locals: { exception: error }
+    end
+
     rescue_from Error::PatronApiError do |error|
       log_error(error)
       render :patron_api_error, status: :service_unavailable

app/views/application/bad_request.html.erb

@@ -0,0 +1,7 @@
+<h1>Bad Request</h1>
+
+<p>Your browser sent a request that the server does not understand.</p>
+
+<% if defined?(exception) && Rails.env.test? %>
+  <%= render(partial: 'exception_details', locals: { exception: exception }) %>
+<% end %>