Improve resilience when executing on providers

[eneufeld]

Currently we have code like this in the different provider-registries:

if (provider) {
    this.logger.debug('Invoking trigger provider(s)');
    result = await provider.getTriggers(modelURI, patch);

    return result;
}

This works fine as long the provider does not end with an error. As we can't rely on this assumption we should wrap the await in a try/catch and handle also the erroneous case.