Function: resolveStorefrontConfig()
resolveStorefrontConfig(
config?,providerName?):StorefrontClientConfig
Resolve a provider config into a complete StorefrontClientConfig, filling
apiUrl / shopSlug from the environment when not passed explicitly.
Throws a clear developer error when a value is still missing after the fallback, so a misconfigured deploy fails loudly at mount instead of sending requests to an empty endpoint. (This is a developer guardrail — not a buyer-facing message.)
Parameters
config?
Optional provider config; apiUrl / shopSlug win over the env.
providerName?
string = 'StorefrontProvider'
Name used in the error message (default StorefrontProvider).