fix(@angular-devkit/schematics): do not ignore TypeErrors thrown by content templates

Since 18.1.0 (41ee8ea), `applyContentTemplate` returns the entry
unchanged for any `TypeError`, so that content which is not valid
UTF-8 is left alone. Decoding and applying the template shared one
`try`, so a `TypeError` thrown by the template itself, such as
`<%= name.length %>` with `name` undefined, also left the file
unrendered without an error. Decode in a separate `try` so that only
decode failures are ignored.

Author: Thanatos9404

packages/angular_devkit/schematics/src/rules/template.ts

@@ -54,13 +54,9 @@ export function applyContentTemplate<T>(options: T): FileOperator {
   return (entry: FileEntry) => {
     const { path, content } = entry;
 
+    let decodedContent: string;
     try {
-      const decodedContent = decoder.decode(content).replace(/\r?\n/g, EOL);
-
-      return {
-        path,
-        content: Buffer.from(templateImpl(decodedContent, {})(options)),
-      };
+      decodedContent = decoder.decode(content);
     } catch (e) {
       // The second part should not be needed. But Jest does not support instanceof correctly.
       // See: https://github.com/jestjs/jest/issues/2549
@@ -73,6 +69,12 @@ export function applyContentTemplate<T>(options: T): FileOperator {
 
       throw e;
     }
+    decodedContent = decodedContent.replace(/\r?\n/g, EOL);
+
+    return {
+      path,
+      content: Buffer.from(templateImpl(decodedContent, {})(options)),
+    };
   };
 }
 

packages/angular_devkit/schematics/src/rules/template_spec.ts

@@ -171,6 +171,18 @@ describe('contentTemplate', () => {
     expect(_applyContentTemplate('a<%= \'a\' + "b" %>b', {})).toBe('aabb');
     expect(_applyContentTemplate('a<%= "\\n" + "b" %>b', {})).toBe('a\nbb');
   });
+
+  it('does not ignore type errors thrown by a template', () => {
+    expect(() => _applyContentTemplate('a<%= value.length %>b', { value: undefined })).toThrowError(
+      /Cannot read properties of undefined/,
+    );
+  });
+
+  it('leaves content that is not valid UTF-8 unchanged', () => {
+    const entry = { path: normalize('/a/b/image.png'), content: Buffer.from([0xff, 0xfe, 0xfd]) };
+
+    expect(applyContentTemplate({})(entry)).toBe(entry);
+  });
 });
 
 describe('applyTemplateFiles', () => {