Remove Bower support.

Retrieving `ember-template-compiler` from `bower_components` is only
required when using Ember versions older than 2.12. Bower itself is
essentially deprecated, this removes the fallback code to use
`bower_components/ember/ember-template-compiler.js` and improves the
error message when we can't actually find `ember-source`.

You can still provide a custom path to the template compiler (and
therefore use Bower if you wish) by:

```js
// ember-cli-build.js

module.exports = function(defaults) {
  let app = new EmberApp(defaults, {
    'ember-cli-htmlbars': {
      templateCompilerPath: `some_path/to/ember-template-compiler.js`,
    }
  });
};
```

lib/ember-addon-main.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const path = require('path');
+const SilentError = require('silent-error');
 const utils = require('./utils');
 
 let registryInvocationCounter = 0;
@@ -191,20 +191,18 @@ module.exports = {
     let templateCompilerPath =
       config['ember-cli-htmlbars'] && config['ember-cli-htmlbars'].templateCompilerPath;
 
-    let ember = this.project.findAddonByName('ember-source');
-    if (ember) {
-      return ember.absolutePaths.templateCompiler;
-    } else if (!templateCompilerPath) {
-      templateCompilerPath = this.project.bowerDirectory + '/ember/ember-template-compiler';
+    if (templateCompilerPath) {
+      return templateCompilerPath;
     }
 
-    let absolutePath = path.resolve(this.project.root, templateCompilerPath);
-
-    if (path.extname(absolutePath) === '') {
-      absolutePath += '.js';
+    let ember = this.project.findAddonByName('ember-source');
+    if (ember) {
+      throw new SilentError(
+        `ember-cli-htmlbars: Cannot find the ember-source addon as part of the project, please ensure that 'ember-source' is in your projects dependencies or devDependencies`
+      );
     }
 
-    return absolutePath;
+    return ember.absolutePaths.templateCompiler;
   },
 
   htmlbarsOptions() {

package.json

@@ -44,6 +44,7 @@
     "heimdalljs-logger": "^0.1.10",
     "json-stable-stringify": "^1.0.1",
     "semver": "^6.3.0",
+    "silent-error": "^1.1.1",
     "strip-bom": "^4.0.0",
     "walk-sync": "^2.0.2"
   },

yarn.lock

@@ -7072,9 +7072,8 @@ mocha@^7.1.1:
     yargs-unparser "1.6.0"
 
 "module-name-inliner@link:./tests/dummy/lib/module-name-inliner":
-  version "0.1.0"
-  dependencies:
-    ember-cli-version-checker "*"
+  version "0.0.0"
+  uid ""
 
 morgan@^1.9.1:
   version "1.9.1"
@@ -8402,6 +8401,13 @@ resolve@^1.1.3, resolve@^1.1.6, resolve@^1.10.0, resolve@^1.10.1, resolve@^1.11.
   dependencies:
     path-parse "^1.0.6"
 
+resolve@^1.13.1:
+  version "1.15.1"
+  resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.15.1.tgz#27bdcdeffeaf2d6244b95bb0f9f4b4653451f3e8"
+  integrity sha512-84oo6ZTtoTUpjgNEr5SJyzQhzL72gaRodsSfyxC/AXRvwu0Yse9H8eF9IpGo7b8YetZhlI6v7ZQ6bKBFV/6S7w==
+  dependencies:
+    path-parse "^1.0.6"
+
 responselike@1.0.2, responselike@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/responselike/-/responselike-1.0.2.tgz#918720ef3b631c5642be068f15ade5a46f4ba1e7"