fix(builtin): fix npm_version_check.js when running outside of bazel (#…

…1802)

internal/npm_version_check.js

@@ -1,15 +1,21 @@
 #!/usr/bin/env node
+
+// Fetch the version of this package from its package.json
 const pkg = require('./package.json');
-const pkgVersion = pkg.version;
-const rules_nodejsVersion = process.env['BUILD_BAZEL_RULES_NODEJS_VERSION'];
+const pkgVersion = pkg.version || '0.0.0';
+
+// BUILD_BAZEL_RULES_NODEJS_VERSION is only set when within the bazel context
+const rulesVersion = process.env['BUILD_BAZEL_RULES_NODEJS_VERSION'] || '0.0.0';
 
-const getMajor = versionString => versionString.split('.')[0];
+const getMajor = versionString => versionString ? versionString.split('.')[0] : '';
 
-// special case the version 0.0.0 so that we don't have to stamp builds
-// for dev and testing
-if (pkgVersion !== '0.0.0' && getMajor(pkgVersion) !== getMajor(rules_nodejsVersion)) {
+// Special cases when either version is 0.0.0.
+// rulesVersion will be 0.0.0 when outside of bazel
+// pkgVersion may be 0.0.0 for dev builds that are not stamped
+if (rulesVersion !== '0.0.0' && pkgVersion !== '0.0.0' &&
+    getMajor(pkgVersion) !== getMajor(rulesVersion)) {
   throw new Error(`Expected package major version to equal @build_bazel_rules_nodejs major version
     ${pkg.name} - ${pkgVersion}  
-    @build_bazel_rules_nodejs - ${rules_nodejsVersion}
+    @build_bazel_rules_nodejs - ${rulesVersion}
   See https://github.com/bazelbuild/rules_nodejs/wiki/Avoiding-version-skew`);
 }