fixes embeddables migrate function (elastic#101470)

src/plugins/embeddable/common/lib/migrate.ts

@@ -26,9 +26,11 @@ export const getMigrateFunction = (embeddables: CommonEmbeddableStartContract) =
     updatedInput.enhancements = {};
     Object.keys(enhancements).forEach((key) => {
       if (!enhancements[key]) return;
-      (updatedInput.enhancements! as Record<string, any>)[key] = embeddables
-        .getEnhancement(key)
-        .migrations[version](enhancements[key] as SerializableState);
+      const enhancementDefinition = embeddables.getEnhancement(key);
+      const migratedEnhancement = enhancementDefinition?.migrations?.[version]
+        ? enhancementDefinition.migrations[version](enhancements[key] as SerializableState)
+        : enhancements[key];
+      (updatedInput.enhancements! as Record<string, any>)[key] = migratedEnhancement;
     });
 
     return updatedInput;

src/plugins/embeddable/public/plugin.test.ts

@@ -184,4 +184,12 @@ describe('embeddable enhancements', () => {
       embeddableState.enhancements.test
     );
   });
+
+  test('doesnt fail if there is no migration function registered for specific version', () => {
+    expect(() => {
+      start.migrate(embeddableState, '7.10.0');
+    }).not.toThrow();
+
+    expect(start.migrate(embeddableState, '7.10.0')).toEqual(embeddableState);
+  });
 });