diff --git a/src/container/EdgeRenderer/MarkerDefinitions.tsx b/src/container/EdgeRenderer/MarkerDefinitions.tsx
index 77d7c4b7..84556b01 100644
--- a/src/container/EdgeRenderer/MarkerDefinitions.tsx
+++ b/src/container/EdgeRenderer/MarkerDefinitions.tsx
@@ -10,7 +10,8 @@ export default defineComponent({
   props: {
     color: {
       type: String as PropType<MarkerDefinitionsProps['color']>,
-      required: true
+      required: false,
+      default: ''
     }
   },
   setup(props) {
diff --git a/src/utils/symbols.ts b/src/utils/symbols.ts
new file mode 100644
index 00000000..e96169fe
--- /dev/null
+++ b/src/utils/symbols.ts
@@ -0,0 +1,7 @@
+import { InjectionKey } from 'vue';
+import { RevueFlowStore } from '../types';
+import { RevueFlowHooks } from '../hooks/RevueFlowHooks';
+
+export const StoreKey: InjectionKey<RevueFlowStore> = Symbol('store');
+export const HooksKey: InjectionKey<RevueFlowHooks> = Symbol('hooks');
+export const NodeIdContextKey: InjectionKey<string> = Symbol('NodeIdContext');