[BUG] Adding an existing source causes app to crash

[albertmoravec]

Platforms

iOS

Version of flutter maplibre_gl

0.20.0

Bug Description

Calling controller.addSource() more than once for the same source causes app crash on iOS with MLNRedundantSourceIdentifierException.

Steps to Reproduce

1. Call controller.addSource('123', VectorSourceProperties(...)).
2. Call controller.addSource('123', VectorSourceProperties(...)) again with the same ID.

Expected Results

Exception should be returned.

Actual Results

App completely crashes with MLNRedundantSourceIdentifierException, not providing any option to handle the exception.

Code Sample

await controller.addSource('123', VectorSourceProperties());
await controller.addSource('123', VectorSourceProperties());