Ensure that rim lighting uses a exponent base greater than zero

This avoids the undefined behavior that happens if the base is zero and the exponent is zero

servers/rendering/renderer_rd/shaders/scene_forward_lights_inc.glsl

@@ -134,7 +134,8 @@ void light_compute(vec3 N, vec3 L, vec3 V, float A, vec3 light_color, float atte
 #endif
 
 #if defined(LIGHT_RIM_USED)
-		float rim_light = pow(max(0.0, 1.0 - cNdotV), max(0.0, (1.0 - roughness) * 16.0));
+		// Epsilon min to prevent pow(0, 0) singularity which results in undefined behavior.
+		float rim_light = pow(max(1e-4, 1.0 - cNdotV), max(0.0, (1.0 - roughness) * 16.0));
 		diffuse_light += rim_light * rim * mix(vec3(1.0), albedo, rim_tint) * light_color;
 #endif