Description of problem:

gitops notification template notify fails with invalid memory address or nil pointer dereference.

When a notication is sent, and the template contains the var reference:
(call .repo.GetAppDetails).Helm.GetParameterValueByName "podLabels.release"
the error "runtime error: invalid memory address or nil pointer dereference" is thrown.

GitHub issue: https://github.com/argoproj/argo-cd/issues/10912

Workaround
No

Prerequisites (if any, like setup, operators/versions):

Gitops version: v1.12.1

Steps to Reproduce
https://github.com/argoproj/argo-cd/issues/10912

Actual results:
Fails with invalid memory address or nil pointer dereference.
failed to notify '<><email>': template: app-deployed:4:4: executing "app-deployed" at <call .repo.GetAppDetails>: error calling call: runtime error: invalid memory address or nil pointer dereference

Expected results:
Notifications template notify to succeed and return the templated text

Reproducibility (Always/Intermittent/Only Once):
Always

Acceptance criteria: 

Definition of Done:

Build Details:
Additional info (Such as Logs, Screenshots, etc):
GitHub issue: https://github.com/argoproj/argo-cd/issues/10912