diff --git a/package.json b/package.json
index b29f890919..fcfa64c244 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,7 @@
     "@types/jasminewd2": "^2.0.3",
     "@types/minimist": "^1.2.0",
     "@types/mock-fs": "^3.6.30",
-    "@types/node": "6.0.88",
+    "@types/node": "^10.9.4",
     "@types/selenium-webdriver": "3.0.7",
     "@types/shelljs": "^0.7.8",
     "@types/source-map": "^0.5.1",
@@ -131,4 +131,4 @@
     "xhr2": "0.1.4",
     "yargs": "9.0.1"
   }
-}
\ No newline at end of file
+}
diff --git a/packages/bazel/test/ng_package/common_package.spec.ts b/packages/bazel/test/ng_package/common_package.spec.ts
index 81d8b32012..4d4e5fedac 100644
--- a/packages/bazel/test/ng_package/common_package.spec.ts
+++ b/packages/bazel/test/ng_package/common_package.spec.ts
@@ -10,7 +10,7 @@ import * as fs from 'fs';
 import * as path from 'path';
 import * as shx from 'shelljs';
 
-shx.cd(path.join(process.env['TEST_SRCDIR'], 'angular', 'packages', 'common', 'npm_package'));
+shx.cd(path.join(process.env['TEST_SRCDIR'] !, 'angular', 'packages', 'common', 'npm_package'));
 
 describe('@angular/common ng_package', () => {
   describe('should have the locales files', () => {
diff --git a/packages/bazel/test/ng_package/core_package.spec.ts b/packages/bazel/test/ng_package/core_package.spec.ts
index 9ebb0001ff..8c92f66c29 100644
--- a/packages/bazel/test/ng_package/core_package.spec.ts
+++ b/packages/bazel/test/ng_package/core_package.spec.ts
@@ -10,7 +10,7 @@ import * as path from 'path';
 import * as shx from 'shelljs';
 
 const corePackagePath =
-    path.join(process.env['TEST_SRCDIR'], 'angular', 'packages', 'core', 'npm_package');
+    path.join(process.env['TEST_SRCDIR'] !, 'angular', 'packages', 'core', 'npm_package');
 shx.cd(corePackagePath);
 
 /**
diff --git a/packages/bazel/test/ngc-wrapped/test_support.ts b/packages/bazel/test/ngc-wrapped/test_support.ts
index 3e331f66d4..a9a674ee40 100644
--- a/packages/bazel/test/ngc-wrapped/test_support.ts
+++ b/packages/bazel/test/ngc-wrapped/test_support.ts
@@ -152,7 +152,7 @@ export function setup(
   function runOneBuildImpl(): boolean { return runOneBuild(['@' + tsConfigJsonPath]); }
 }
 
-function makeTempDir(baseDir): string {
+function makeTempDir(baseDir: string): string {
   const id = (Math.random() * 1000000).toFixed(0);
   const dir = path.join(baseDir, `tmp.${id}`);
   fs.mkdirSync(dir);
diff --git a/packages/compiler-cli/src/transformers/program.ts b/packages/compiler-cli/src/transformers/program.ts
index 8315f0e1a5..3cf68e000d 100644
--- a/packages/compiler-cli/src/transformers/program.ts
+++ b/packages/compiler-cli/src/transformers/program.ts
@@ -1021,7 +1021,7 @@ export function i18nExtract(
   const ext = i18nGetExtension(formatName);
   const content = i18nSerialize(bundle, formatName, options);
   const dstFile = outFile || `messages.${ext}`;
-  const dstPath = path.resolve(options.outDir || options.basePath, dstFile);
+  const dstPath = path.resolve(options.outDir || options.basePath !, dstFile);
   host.writeFile(dstPath, content, false, undefined, []);
   return [dstPath];
 }
diff --git a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
index 1d6045500e..05999b40d9 100644
--- a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
+++ b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
@@ -14,6 +14,9 @@ import {main, readCommandLineAndConfiguration, watchMode} from '../../src/main';
 import {TestSupport, isInBazel, makeTempDir, setup} from '../test_support';
 
 function setupFakeCore(support: TestSupport): void {
+  if (!process.env.TEST_SRCDIR) {
+    throw new Error('`setupFakeCore` must be run within a Bazel test');
+  }
   const fakeCore = path.join(
       process.env.TEST_SRCDIR, 'angular/packages/compiler-cli/test/ngtsc/fake_core/npm_package');
 
diff --git a/packages/compiler-cli/test/test_support.ts b/packages/compiler-cli/test/test_support.ts
index 1dcb259018..128c3f9750 100644
--- a/packages/compiler-cli/test/test_support.ts
+++ b/packages/compiler-cli/test/test_support.ts
@@ -110,6 +110,9 @@ function createTestSupportFor(basePath: string) {
 }
 
 export function setupBazelTo(basePath: string) {
+  if (!process.env.TEST_SRCDIR) {
+    throw new Error('`setupBazelTo()` must only be called from in a Bazel job.');
+  }
   const sources = process.env.TEST_SRCDIR;
   const packages = path.join(sources, 'angular/packages');
   const nodeModulesPath = path.join(basePath, 'node_modules');
diff --git a/yarn.lock b/yarn.lock
index 3b9c87b183..28f365726d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -106,9 +106,9 @@
   version "10.5.2"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-10.5.2.tgz#f19f05314d5421fe37e74153254201a7bf00a707"
 
-"@types/node@6.0.88":
-  version "6.0.88"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-6.0.88.tgz#f618f11a944f6a18d92b5c472028728a3e3d4b66"
+"@types/node@^10.9.4":
+  version "10.9.4"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-10.9.4.tgz#0f4cb2dc7c1de6096055357f70179043c33e9897"
 
 "@types/node@^6.0.46":
   version "6.0.114"