[BUGFIX lts] Ensure errors in deferred component hooks can be recovered.

Previously, any errors thrown during `didInsertElement` would leave the
running environment in an invalid state (`env.inTransaction` would be
`true` but `this._transaction` would have been nullified).

This commit ensures that we _always_ reset `inTransaction` if
`Environment.prototype.commit` is called. Thus avoiding an error RE:
"calling commit on null"...

packages/ember-glimmer/lib/environment.ts

@@ -207,9 +207,11 @@ export default class Environment extends GlimmerEnvironment {
       destroyedComponents[i].destroy();
     }
 
-    super.commit();
-
-    this.inTransaction = false;
+    try {
+      super.commit();
+    } finally {
+      this.inTransaction = false;
+    }
   }
 }
 

packages/ember-glimmer/tests/integration/components/error-handling-test.js

@@ -69,4 +69,59 @@ moduleFor('Errors thrown during render', class extends RenderingTest {
 
     this.assertText('hello');
   }
+
+  ['@test it can recover resets the transaction when an error is thrown during didInsertElement'](assert) {
+    let shouldThrow = true;
+    let FooBarComponent = Component.extend({
+      didInsertElement() {
+        this._super(...arguments);
+        if (shouldThrow) {
+          throw new Error('silly mistake!');
+        }
+      }
+    });
+
+    this.registerComponent('foo-bar', { ComponentClass: FooBarComponent, template: 'hello' });
+
+    assert.throws(() => {
+      this.render('{{#if switch}}{{#foo-bar}}{{foo-bar}}{{/foo-bar}}{{/if}}', { switch: true });
+    }, /silly mistake/);
+
+    assert.equal(this.env.inTransaction, false, 'should not be in a transaction even though an error was thrown');
+
+    this.assertText('hello');
+
+    this.runTask(() => set(this.context, 'switch', false));
+
+    this.assertText('');
+  }
+
+  ['@test it can recover resets the transaction when an error is thrown during destroy'](assert) {
+    let shouldThrow = true;
+    let FooBarComponent = Component.extend({
+      destroy() {
+        this._super(...arguments);
+        if (shouldThrow) {
+          throw new Error('silly mistake!');
+        }
+      }
+    });
+
+    this.registerComponent('foo-bar', { ComponentClass: FooBarComponent, template: 'hello' });
+
+    this.render('{{#if switch}}{{#foo-bar}}{{foo-bar}}{{/foo-bar}}{{/if}}', { switch: true });
+
+    this.assertText('hello');
+
+    assert.throws(() => {
+      this.runTask(() => set(this.context, 'switch', false));
+    }, /silly mistake/);
+
+    this.assertText('');
+
+    shouldThrow = false;
+    this.runTask(() => set(this.context, 'switch', true));
+
+    this.assertText('hello');
+  }
 });