Proposed changes

Fixes #6674

Replaced a panic with proper error handling in the template loader when GetDialersWithId() returns nil, since this can occur in non-scanning paths where dialers aren’t initialized.

Proof

• make test - all unit tests pass
• make vet - passes with no issues
• make build - compiles successfully

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

/claim #6674