[Bug] Web App (https://app.zenuml.com) always load the same diagram instead of previous diagram

[MrCoder]

Reproduce steps:

1. Open https://app.zenuml.com
2. Login if you have not
3. Create a diagram, if it did not open a diagram automatically
4. Save this diagram
5. Create a new diagram
6. Save the new diagram
7. Refresh the page.

Expected result:
It should load the diagram created on step 5.

Actual result:
It loads the diagram created on step 3.

[whimet]

#626