Fix bad parameter for rendering_method crashes Godot

[jsjtxietian]

Print error and default to forward plus. Prevent it crash is always necessary I suppose, but maybe we can default to other rendering method?

Fixes #69815

[akien-mga]

In my previous review comment, I also suggested doing this, to be consistent:

diff --git a/servers/rendering/renderer_rd/renderer_compositor_rd.cpp b/servers/rendering/renderer_rd/renderer_compositor_rd.cpp
index b9bda9329e..d09cd8a615 100644
--- a/servers/rendering/renderer_rd/renderer_compositor_rd.cpp
+++ b/servers/rendering/renderer_rd/renderer_compositor_rd.cpp
@@ -310,10 +310,10 @@ RendererCompositorRD::RendererCompositorRD() {
 	uint64_t textures_per_stage = RD::get_singleton()->limit_get(RD::LIMIT_MAX_TEXTURES_PER_SHADER_STAGE);
 
 	if (rendering_method == "mobile" || textures_per_stage < 48) {
-		scene = memnew(RendererSceneRenderImplementation::RenderForwardMobile());
 		if (rendering_method == "forward_plus") {
 			WARN_PRINT_ONCE("Platform supports less than 48 textures per stage which is less than required by the Clustered renderer. Defaulting to Mobile renderer.");
 		}
+		scene = memnew(RendererSceneRenderImplementation::RenderForwardMobile());
 	} else if (rendering_method == "forward_plus") {
 		// default to our high end renderer
 		scene = memnew(RendererSceneRenderImplementation::RenderForwardClustered());

First we warn, then we instantiate the fallback.

[akien-mga]

Thanks!

[YuriSizov]

Cherry-picked for 4.2.1.

[YuriSizov]

Cherry-picked for 4.1.4.