[Bug #4529] Fix graph partial validation failure (#4588)

Currently, if a graph partially fails validation (i.e. some outputs are
valid while others have links from missing nodes), the execution loop
could get an exception resulting in server lockup.

This isn't actually possible to reproduce via the default UI, but is a
potential issue for people using the API to construct invalid graphs.

comfy_execution/caching.py

@@ -56,6 +56,8 @@ class CacheKeySetID(CacheKeySet):
         for node_id in node_ids:
             if node_id in self.keys:
                 continue
+            if not self.dynprompt.has_node(node_id):
+                continue
             node = self.dynprompt.get_node(node_id)
             self.keys[node_id] = (node_id, node["class_type"])
             self.subcache_keys[node_id] = (node_id, node["class_type"])
@@ -74,6 +76,8 @@ class CacheKeySetInputSignature(CacheKeySet):
         for node_id in node_ids:
             if node_id in self.keys:
                 continue
+            if not self.dynprompt.has_node(node_id):
+                continue
             node = self.dynprompt.get_node(node_id)
             self.keys[node_id] = self.get_node_signature(self.dynprompt, node_id)
             self.subcache_keys[node_id] = (node_id, node["class_type"])
@@ -87,6 +91,9 @@ class CacheKeySetInputSignature(CacheKeySet):
         return to_hashable(signature)
 
     def get_immediate_node_signature(self, dynprompt, node_id, ancestor_order_mapping):
+        if not dynprompt.has_node(node_id):
+            # This node doesn't exist -- we can't cache it.
+            return [float("NaN")]
         node = dynprompt.get_node(node_id)
         class_type = node["class_type"]
         class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
@@ -112,6 +119,8 @@ class CacheKeySetInputSignature(CacheKeySet):
         return ancestors, order_mapping
 
     def get_ordered_ancestry_internal(self, dynprompt, node_id, ancestors, order_mapping):
+        if not dynprompt.has_node(node_id):
+            return
         inputs = dynprompt.get_node(node_id)["inputs"]
         input_keys = sorted(inputs.keys())
         for key in input_keys:

tests/inference/test_execution.py

@@ -357,6 +357,25 @@ class TestExecution:
             assert 'prompt_id' in e.args[0], f"Did not get back a proper error message: {e}"
             assert e.args[0]['node_id'] == generator.id, "Error should have been on the generator node"
 
+    def test_missing_node_error(self, client: ComfyClient, builder: GraphBuilder):
+        g = builder
+        input1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        input2 = g.node("StubImage", id="removeme", content="WHITE", height=512, width=512, batch_size=1)
+        input3 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+        mask = g.node("StubMask", value=0.5, height=512, width=512, batch_size=1)
+        mix1 = g.node("TestLazyMixImages", image1=input1.out(0), image2=input2.out(0), mask=mask.out(0))
+        mix2 = g.node("TestLazyMixImages", image1=input1.out(0), image2=input3.out(0), mask=mask.out(0))
+        # We have multiple outputs. The first is invalid, but the second is valid
+        g.node("SaveImage", images=mix1.out(0))
+        g.node("SaveImage", images=mix2.out(0))
+        g.remove_node("removeme")
+        
+        client.run(g)
+
+        # Add back in the missing node to make sure the error doesn't break the server
+        input2 = g.node("StubImage", id="removeme", content="WHITE", height=512, width=512, batch_size=1)
+        client.run(g)
+
     def test_custom_is_changed(self, client: ComfyClient, builder: GraphBuilder):
         g = builder
         # Creating the nodes in this specific order previously caused a bug
@@ -450,8 +469,8 @@ class TestExecution:
         g = builder
         input1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
 
-        output1 = g.node("PreviewImage", images=input1.out(0))
-        output2 = g.node("PreviewImage", images=input1.out(0))
+        output1 = g.node("SaveImage", images=input1.out(0))
+        output2 = g.node("SaveImage", images=input1.out(0))
 
         result = client.run(g)
         images1 = result.get_images(output1)