Refresh package managers after setup (#4397)

* Refresh package managers after setup
* Fix default plugins/scrapers paths

internal/api/resolver_query_package.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"errors"
+	"fmt"
 	"sort"
 	"strings"
 
@@ -26,6 +27,10 @@ func getPackageManager(typeArg PackageType) (*pkg.Manager, error) {
 		return nil, ErrInvalidPackageType
 	}
 
+	if pm == nil {
+		return nil, fmt.Errorf("%s package manager not initialized", typeArg)
+	}
+
 	return pm, nil
 }