Hi Katharina,
I have exactly the same issue.I am not using google maps. I just created an extension for appointments app and it works fine in Web IDE , but on the launchpad it gives the below issue.
Error: failed to load 'sap/cus/crm/lib/reuse/library.js' from /sap/bc/ui5_ui5/ui2/ushell/resources/sap/cus/crm/lib/reuse/library.js: 404 - NOT FOUND
Can you please let me know if you were able to resolve your problem. It will be great if you can share your findings.
Thanks,
Vivek