Fix fatal error using GF Google Analytics Pagination feature

[jakejackson1]

Description

Use the passed $form and $entry object when processing, as $entry may be created before submission and $gform->get_entry() will return a WP_Error in this instance. This is the case when using the Pagination feature in the GF Google Analytics plugin.

Checklist:

• [x] I've tested the code.
• [x] My code is easy to read, follow, and understand
• [ ] My code follows the accessibility standards.
• [x] My code has proper inline documentation / docblocks.

Additional Comments

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (0889cdd) 75.13% compared to head (e4479e8) 93.30%.

:exclamation: Current head e4479e8 differs from pull request most recent head 74b7254. Consider uploading reports for the commit 74b7254 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #1479 +/- ## ================================================== + Coverage 75.13% 93.30% +18.16% ================================================== Files 243 57 -186 Lines 12880 1464 -11416 Branches 370 370 ================================================== - Hits 9678 1366 -8312 + Misses 3194 90 -3104 Partials 8 8 ```

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