intl: (v4.x) Don't crash if v8BreakIterator not available

If the undocumented v8BreakIterator does not have data available,
monkeypatch it to throw an error instead of crashing.

Backport of nodejs#3111 c99f231

src/node.cc

@@ -2855,6 +2855,13 @@ void SetupProcessObject(Environment* env,
   READONLY_PROPERTY(versions,
                     "icu",
                     OneByteString(env->isolate(), U_ICU_VERSION));
+
+  if (icu_data_dir != nullptr) {
+    // Did the user attempt (via env var or parameter) to set an ICU path?
+    READONLY_PROPERTY(process,
+                      "icu_data_dir",
+                      OneByteString(env->isolate(), icu_data_dir));
+  }
 #endif
 
   const char node_modules_version[] = NODE_STRINGIFY(NODE_MODULE_VERSION);

src/node.js

@@ -266,6 +266,22 @@
     process.config = JSON.parse(config, function(key, value) {
       if (value === 'true') return true;
       if (value === 'false') return false;
+
+      // Intl.v8BreakIterator() would crash w/ fatal error, so throw instead.
+      if (value.icu_small &&
+          global.hasOwnProperty('Intl') &&
+          Intl.hasOwnProperty('v8BreakIterator') &&
+          !process.icu_data_dir) {
+        const des = Object.getOwnPropertyDescriptor(Intl, 'v8BreakIterator');
+        des.value = function v8BreakIterator() {
+          throw new Error('v8BreakIterator: full ICU data not installed. ' +
+                          'See https://github.com/nodejs/node/wiki/Intl');
+        };
+        Object.defineProperty(Intl, 'v8BreakIterator', des);
+      }
+      // Don’t let icu_data_dir leak through.
+      delete process.icu_data_dir;
+
       return value;
     });
   };

test/parallel/test-intl-v8BreakIterator.js

@@ -0,0 +1,15 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+
+if (global.Intl === undefined || Intl.v8BreakIterator === undefined) {
+  return console.log('1..0 # Skipped: no Intl');
+}
+
+try {
+  new Intl.v8BreakIterator();
+  // May succeed if data is available - OK
+} catch (e) {
+  // May throw this error if ICU data is not available - OK
+  assert.throws(() => new Intl.v8BreakIterator(), /ICU data/);
+}