Warnings are printed as errors on the web platform

### Tested versions

- Reproducible in: 4.3.stable

### System information

Godot v4.3.stable - Firefox 132, Chromium 130 - X11 - OpenGL (Compatibility) - dedicated NVIDIA GeForce RTX 4090 (nvidia; 565.57.01) - 13th Gen Intel(R) Core(TM) i9-13900K (32 Threads)

### Issue description

In the browser's devtools, all warnings appear as errors:


They should appear using warnings instead, similar to `console.warn()`.

### Steps to reproduce

Export a project that calls `push_warning()` or uses unsupported features in the Compatibility rendering method, such as https://github.com/godotengine/godot-demo-projects/tree/master/2d/particles.

### Minimal reproduction project (MRP)

https://godotengine.github.io/godot-demo-projects/2d/particles/

Start by tracing how push_warning() and unsupported Compatibility-rendering warnings reach the browser's devtools during a web export, using the 2d/particles demo project to reproduce the behavior. Compare the current output with console.warn(); done means warnings appear as browser warnings rather than errors.

Written by the indexing model from the issue text.