[theming]: Load multiple themes

Bug Description

Hi,

we do have multiple custom themes. In our openUI5 projects we have no problem loading them, in our new projects using the UI5 Web Components it does not work. This is currently a major blocker for us.

I found this question in https://github.com/UI5/webcomponents/issues/1737#issuecomment-641198446 but no proper answer.

If i include multiple themes it only loads the last one properly. If i try to select any other i get the error: You have requested a non-registered theme

Is it currently possible to add multiple custom themes? This is not clear in the documentation for me and all examples i found are only using one theme.

Affected Component

No response

Expected Behaviour

Include multiple themes as described in the documentation: https://ui5.github.io/webcomponents/docs/advanced/theming-part2/
Select any of the custom themes should work.

Isolated Example

https://github.com/fk-aconso/ui5-webcomponents

Steps to Reproduce

1. Add multiple themes
2. Select any theme: Only the last one will work.

Log Output, Stack Trace or Screenshots

@ui5_webcomponents_d…s.js?v=f2f8f665:937 You have requested a non-registered theme testgreen - falling back to sap_horizon. Registered themes are: sap_horizon
getThemeProperties	@	@ui5_webcomponents_d…s.js?v=f2f8f665:937
loadThemeBase	@	@ui5_webcomponents_d….js?v=f2f8f665:1110
applyTheme	@	@ui5_webcomponents_d….js?v=f2f8f665:1155
await in applyTheme

Priority

None

UI5 Web Components Version

2.15.1

Browser

Firefox

Operating System

No response

Additional Context

No response

Organization

aconso

Declaration

• I’m not disclosing any internal or sensitive information.