feat(ui): add type guards for outputs

invokeai/frontend/web/src/services/types/guards.ts

@@ -0,0 +1,33 @@
+import {
+  GraphExecutionState,
+  GraphInvocationOutput,
+  ImageOutput,
+  MaskOutput,
+  PromptOutput,
+  IterateInvocationOutput,
+  CollectInvocationOutput,
+} from 'services/api';
+
+export const isImageOutput = (
+  output: GraphExecutionState['results'][string]
+): output is ImageOutput => output.type === 'image';
+
+export const isMaskOutput = (
+  output: GraphExecutionState['results'][string]
+): output is MaskOutput => output.type === 'mask';
+
+export const isPromptOutput = (
+  output: GraphExecutionState['results'][string]
+): output is PromptOutput => output.type === 'prompt';
+
+export const isGraphOutput = (
+  output: GraphExecutionState['results'][string]
+): output is GraphInvocationOutput => output.type === 'graph_output';
+
+export const isIterateOutput = (
+  output: GraphExecutionState['results'][string]
+): output is IterateInvocationOutput => output.type === 'iterate_output';
+
+export const isCollectOutput = (
+  output: GraphExecutionState['results'][string]
+): output is CollectInvocationOutput => output.type === 'collect_output';