Fix #147340: EEVEE: Crash on failed world material compilation

- Check for failed World materials.
- Remove invalid links (unsure about this one).

(4.5 LTS backport candidate)

Pull Request: https://projects.blender.org/blender/blender/pulls/147445

source/blender/draw/engines/eevee/eevee_world.cc

@@ -120,6 +120,12 @@ void World::sync()
 
   GPUMaterial *gpumat = inst_.shaders.world_shader_get(
       bl_world, ntree, MAT_PIPE_DEFERRED, !wait_ready);
+
+  if (GPU_material_status(gpumat) == GPU_MAT_FAILED) {
+    bl_world = default_world_get();
+    ntree = bl_world->nodetree;
+    gpumat = inst_.shaders.world_shader_get(bl_world, ntree, MAT_PIPE_DEFERRED, !wait_ready);
+  }
   if (GPU_material_status(gpumat) == GPU_MAT_QUEUED) {
     is_ready_ = false;
     return;

source/blender/nodes/shader/node_shader_tree.cc

@@ -434,10 +434,9 @@ static bool ntree_shader_implicit_closure_cast(bNodeTree *ntree)
       modified = true;
     }
     else if ((link->fromsock->type == SOCK_SHADER) && (link->tosock->type != SOCK_SHADER)) {
-      /* Meh. Not directly visible to the user. But better than nothing. */
-      fprintf(stderr, "Shader Nodetree Error: Invalid implicit socket conversion\n");
+      blender::bke::node_remove_link(ntree, *link);
       BKE_ntree_update_after_single_tree_change(*G.main, *ntree);
-      return false;
+      modified = true;
     }
   }
   if (modified) {