fix error creation

Author: appilon

diag/diagnostic.go

@@ -1,6 +1,7 @@
 package diag
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/zclconf/go-cty/cty"
@@ -36,7 +37,7 @@ func (d Diagnostic) Validate() error {
 		return fmt.Errorf("invalid severity: %v", d.Severity)
 	}
 	if d.Summary == "" {
-		return fmt.Errorf("empty detail")
+		return errors.New("empty detail")
 	}
 	return nil
 }

helper/schema/resource.go

@@ -382,7 +382,10 @@ func (r *Resource) Apply(
 		diags = append(diags, r.create(ctx, data, meta)...)
 	} else {
 		if !r.updateFuncSet() {
-			return s, append(diags, diag.FromErr(fmt.Errorf("doesn't support update")))
+			return s, append(diags, diag.Diagnostic{
+				Severity: diag.Error,
+				Summary:  "doesn't support update",
+			})
 		}
 		diags = append(diags, r.update(ctx, data, meta)...)
 	}