refactor: remove unrelated function and add input validation

- Remove findChangelogInsertionPoint function (unrelated to flavor recognition)
- Add type validation to extractPRFlavor to prevent runtime errors
- Add comprehensive tests for input validation
- Reduce test count from 23 to 18 focused tests

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: vaind

danger/dangerfile-utils.js

@@ -57,13 +57,14 @@ function getFlavorConfig(prFlavor) {
 
 /// Extract PR flavor from title or branch name
 function extractPRFlavor(prTitle, prBranchRef) {
-  if (prTitle) {
+  // Validate input parameters to prevent runtime errors
+  if (prTitle && typeof prTitle === 'string') {
     const parts = prTitle.split(":");
     if (parts.length > 1) {
       return parts[0].toLowerCase().trim();
     }
   }
-  if (prBranchRef) {
+  if (prBranchRef && typeof prBranchRef === 'string') {
     const parts = prBranchRef.split("/");
     if (parts.length > 1) {
       return parts[0].toLowerCase();

danger/dangerfile-utils.test.js

@@ -141,6 +141,27 @@ describe('dangerfile-utils', () => {
       const flavor3 = extractPRFlavor('title: with: multiple: colons', null);
       assert.strictEqual(flavor3, 'title');
     });
+
+    it('should validate input parameters and handle non-string types', () => {
+      // Number inputs
+      const flavor1 = extractPRFlavor(123, 456);
+      assert.strictEqual(flavor1, '');
+
+      // Object inputs
+      const flavor2 = extractPRFlavor({ test: 'object' }, ['array']);
+      assert.strictEqual(flavor2, '');
+
+      // Boolean inputs
+      const flavor3 = extractPRFlavor(true, false);
+      assert.strictEqual(flavor3, '');
+
+      // Mixed valid/invalid inputs
+      const flavor4 = extractPRFlavor(null, 'valid/branch');
+      assert.strictEqual(flavor4, 'valid');
+
+      const flavor5 = extractPRFlavor('valid: title', 42);
+      assert.strictEqual(flavor5, 'valid');
+    });
   });