chore(plugin): better error msg (#4446)

* chore(plugin): better error msg

* lint

* Update plugin.go

Co-authored-by: Danny <danny.f.salman@gmail.com>

* Update plugin.go

---------

Co-authored-by: Danny <danny.f.salman@gmail.com>

ignite/cmd/plugin.go

@@ -512,7 +512,11 @@ Respects key value pairs declared after the app path to be added to the generate
 			}
 			defer plugins[0].KillClient()
 
-			if plugins[0].Error != nil {
+			if err := plugins[0].Error; err != nil {
+				if strings.Contains(err.Error(), "go.mod file not found in current directory") {
+					return errors.Errorf("unable to find an App at the root of this repository (%s). Please ensure your repository URL is correct. If you're trying to install an App under a subfolder, include the path at the end of your repository URL, e.g., github.com/ignite/apps/appregistry", args[0])
+				}
+
 				return errors.Errorf("error while loading app %q: %w", args[0], plugins[0].Error)
 			}
 			session.Println(icons.OK, "Done loading apps")