fix: check for file content before converting to buffer (github) (#925)

lib/api/github.js

@@ -663,7 +663,10 @@ async function getFileContent(filePath, branchName) {
   );
   try {
     const file = await getFile(filePath, branchName);
+    if (file) {
       return Buffer.from(file, 'base64').toString();
+    }
+    return null;
   } catch (error) {
     if (error.statusCode === 404) {
       // If file not found, then return null JSON

test/api/__snapshots__/github.spec.js.snap

@@ -832,6 +832,35 @@ Array [
 ]
 `;
 
+exports[`api/github getFileContent(filePatch, branchName) should return null if getFile returns nothing 1`] = `
+Array [
+  Array [
+    "repos/some/repo",
+    Object {
+      "headers": Object {
+        "accept": "application/vnd.github.loki-preview+json",
+      },
+    },
+  ],
+  Array [
+    "repos/some/repo/git/refs/heads/master",
+    undefined,
+  ],
+  Array [
+    "repos/some/repo/branches/master/protection/required_status_checks",
+    Object {
+      "headers": Object {
+        "accept": "application/vnd.github.loki-preview+json",
+      },
+    },
+  ],
+  Array [
+    "repos/some/repo/contents/package.json?ref=master",
+    undefined,
+  ],
+]
+`;
+
 exports[`api/github getFileContent(filePatch, branchName) should return the encoded file content 1`] = `
 Array [
   Array [

test/api/github.spec.js

@@ -1497,6 +1497,15 @@ describe('api/github', () => {
       expect(ghGot.mock.calls).toMatchSnapshot();
       expect(content).toBe(null);
     });
+    it('should return null if getFile returns nothing', async () => {
+      await initRepo('some/repo', 'token');
+      ghGot.mockImplementationOnce(() => ({
+        body: {},
+      }));
+      const content = await github.getFileContent('package.json');
+      expect(ghGot.mock.calls).toMatchSnapshot();
+      expect(content).toBe(null);
+    });
     it('should return propagate unknown errors', async () => {
       await initRepo('some/repo', 'token');
       ghGot.mockImplementationOnce(() => {