in .fire always set calling flag back to false (#1573)

src/shared/index.js

@@ -47,11 +47,14 @@ export function fire(eventName, data) {
 		var handler = handlers[i];
 
 		if (!handler.__calling) {
+			try {
 				handler.__calling = true;
 				handler.call(this, data);
+			} finally {
 				handler.__calling = false;
 			}
 		}
+	}
 }
 
 export function get() {

test/runtime/samples/component-events-fire-finally/_config.js

@@ -0,0 +1,23 @@
+export default {
+	test(assert, component) {
+		const events = [];
+		component.on('foo', (shouldThrow) => {
+			events.push(shouldThrow);
+			if (shouldThrow) {
+				throw new Error();
+			}
+		});
+		component.fire('foo', false);
+		assert.equal(events.toString(), 'false');
+		let threw = false;
+		try {
+			component.fire('foo', true);
+		} catch (err) {
+			threw = true;
+		}
+		assert.equal(threw, true);
+		assert.equal(events.toString(), 'false,true');
+		component.fire('foo', false);
+		assert.equal(events.toString(), 'false,true,false');
+	},
+};

test/runtime/samples/component-events-fire-finally/main.html

@@ -0,0 +1 @@
+Foo