Do not crash when stopping already stopped interpreter. Fixes #1697

statelyai · Dec 9, 2020 · fe5ebd3 · fe5ebd3
1 parent a5e4e78
commit fe5ebd3
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diff --git a/packages/core/src/interpreter.ts b/packages/core/src/interpreter.ts
@@ -503,6 +503,11 @@ export class Interpreter<
       this.doneListeners.delete(listener);
     }
 
+    if (!this.initialized) {
+      // Interpreter already stopped; do nothing
+      return this;
+    }
+
     this.state.configuration.forEach((stateNode) => {
       for (const action of stateNode.definition.exit) {
         this.exec(action, this.state);

diff --git a/packages/core/test/interpreter.test.ts b/packages/core/test/interpreter.test.ts
@@ -1388,6 +1388,19 @@ Event: {\\"type\\":\\"SOME_EVENT\\"}"
         done();
       }, 10);
     });
+
+    it('stopping a not-started interpreter should not crash', () => {
+      const service = interpret(
+        createMachine({
+          initial: 'a',
+          states: { a: {} }
+        })
+      );
+
+      expect(() => {
+        service.stop();
+      }).not.toThrow();
+    });
   });
 
   describe('off()', () => {