Throw error on bad input

lib/shopify_api/session.rb

@@ -144,16 +144,6 @@ def api_version=(version)
       end
     end
 
-    def access_scopes=(access_scopes)
-      return unless access_scopes
-
-      @access_scopes = begin
-        ShopifyAPI::ApiAccess.new(access_scopes)
-      rescue
-        nil
-      end
-    end
-
     def valid?
       domain.present? && token.present? && api_version.is_a?(ApiVersion)
     end
@@ -191,6 +181,11 @@ def state
 
     private
 
+    def access_scopes=(access_scopes)
+      return unless access_scopes
+      @access_scopes = ShopifyAPI::ApiAccess.new(access_scopes)
+    end
+
     def parameterize(params)
       URI.escape(params.collect { |k, v| "#{k}=#{v}" }.join('&'))
     end

test/session_test.rb

@@ -103,14 +103,15 @@ def setup
     assert_equal "read_products", session.access_scopes.to_s
   end
 
-  test "set access_scopes to nil if bad access scopes are provided" do
-    session = ShopifyAPI::Session.new(
-      domain: "testshop.myshopify.com",
-      token: "any-token",
-      access_scopes: { bad_input: "bad_input" },
-      api_version: any_api_version
-    )
-    assert_nil session.access_scopes
+  test "session instantiation raises error if bad access scopes are provided" do
+    assert_raises do
+      ShopifyAPI::Session.new(
+        domain: "testshop.myshopify.com",
+        token: "any-token",
+        access_scopes: { bad_input: "bad_input" },
+        api_version: any_api_version
+      )
+    end
   end
 
   test "raise error if params passed but signature omitted" do