Add error message or disable Waiter window

[vpchung]

Is your feature request related to a problem? Please describe.
I was testing out changes on the CSBC/PS-ON DCA, and attempted to generate a template link to understand how the app works. However, something broke in the backend and I didn't notice right away because the error message was hidden under the "Generating link..." window:

Describe the solution you'd like
Add a more prominent error message, or disable the Waiter window once an error is encountered.

How important is this feature? Select from the options below:
🌗 Medium (not a huge deal, but it did take me about 5 minutes before realizing that nothing was happening 😅)

When will use cases depending on this become relevant? Select from the options below:
• Mid-term - 2-4 months ?

[rrchai]

AC:
Wrap the function generating the manifest within tryCatch to better capture errors and update waiter once error is encountered.