Unexpected behaviour when `projection` is not specified in style

[ztzthu]

maplibre-gl-js version: 5.14.0 (latest)

Steps to Trigger Behavior

1. In the style document if I do not specify the projection, then the default projection is mercator as per the documentation.
2. In this case map.getProjection() returns undefined, which is understandable because the projection is not defined after all.
3. I explicitly set the projection to mercator using map.setProjection()
4. map.getProjection() still returns undefined - this is unexpected.
5. Setting the projection to globe to an undefined projection has the correct behaviour though.

Link to Demonstration

Minimal example

Expected Behavior

1. After map.setProjection({type: "mercator"}) to an undefined style, map.getProjection() should return mercator.
2. If map.getProjection() is allowed to return undefined, then the wording in the style documentation

Optional projectionDefinition. Defaults to "mercator".

should be improved to

Optional projectionDefinition. If not specified the map will be rendered as if "mercator" projection is used.

Actual Behavior

See Steps to Trigger Behavior

Use-case

I had this problem because I wanted to define the projection based on zoom values. I also needed to dynamically set the projection at initialzation based on zoom level, hence there was no default projection defined.

[HarelM]

Probably early return when this is the same.
Feel free to look into it.