code: protected function createProviderInstance($provider)
      {
          if (! $this->isProviderAliasExists($provider)) {
              throw new InvalidArgumentException("File provider [{$provider}] is invalid.");
          }
  
          if (! isset($this->resolvedProviders[$provider])) {
              $this->resolvedProviders[$provider] = isset($this->customProviders[$provider])
                  ? $this->callCustomProvider($provider)
                  : $this->app->make($this->providers[$provider]);
          }
  
          return $this->resolvedProviders[$provider];
      }
docs: Create the file provider instance.
  
  @param  string  $provider
  @return \Rymanalu\LaravelSimpleUploader\Contracts\Provider
  
  @throws \InvalidArgumentException