Fix app shell not listening to provider (#32)

src/dbp-signature.js

@@ -2,5 +2,6 @@ import {AppShell} from '@dbp-toolkit/app-shell';
 import * as commonUtils from '@dbp-toolkit/common/utils';
 import {Provider} from '@dbp-toolkit/provider';
 
+// It's important that the Provider is created before the AppShell, so the AppShell can subscribe to the Provider
+commonUtils.defineCustomElement('dbp-provider', Provider);
 commonUtils.defineCustomElement('dbp-signature', AppShell);
-commonUtils.defineCustomElement('dbp-provider', Provider);
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