Investigate getConsent throw "PlatformException" when the value is missing

### Prerequisites

- [x] This is not a Security Disclosure, otherwise please follow the guidelines in [Security Policy](https://github.com/adobe/aepsdk_flutter/security/policy).
- [x] I have searched in this repository's issues to see if it has already been reported.
- [x] I have updated to the latest released version of the SDK and the issue still persists.

### Bug summary

getConsent API throw "PlatformException" when the value is missing.

Expected:
To return null or an empty map.

### Environment

N/A

### Steps to reproduce

_No response_

### Current behavior

_No response_

### Expected behavior

_No response_

### Anything else?

_No response_

Start by reproducing the getConsent API call when the consent value is missing, since the issue provides no file, test, or reproduction steps. Trace the SDK path that turns the missing value into PlatformException; the work is done when the API returns null or an empty map instead and the behavior is covered by a regression test.

Written by the indexing model from the issue text.