errors: eliminate circular dependency on assert

Author: jasnell

lib/internal/errors.js

@@ -12,7 +12,6 @@ const kCode = Symbol('code');
 const messages = new Map();
 
 // Lazily loaded
-var assert = null;
 var util = null;
 
 function makeNodeError(Base) {
@@ -55,9 +54,20 @@ class AssertionError extends Error {
   }
 }
 
+// This is defined here instead of using the assert module to avoid a
+// circular dependency. The effect is largely the same.
+function assert(condition, message) {
+  if (!condition) {
+    throw new AssertionError({
+      message,
+      actual: false,
+      expected: true,
+      operator: '=='
+    });
+  }
+}
+
 function message(key, args) {
-  if (assert === null) assert = require('assert');
-  assert.strictEqual(typeof key, 'string');
   const msg = messages.get(key);
   assert(msg, `An invalid error message key was used: ${key}.`);
   let fmt;
@@ -188,7 +198,7 @@ E('ERR_INDEX_OUT_OF_RANGE', 'Index out of range');
 E('ERR_INVALID_ARG_TYPE', invalidArgType);
 E('ERR_INVALID_ARRAY_LENGTH',
   (name, len, actual) => {
-    assert.strictEqual(typeof actual, 'number');
+    assert(typeof actual === 'number', 'actual must be a number');
     return `The array "${name}" (length ${actual}) must be of length ${len}.`;
   });
 E('ERR_INVALID_ASYNC_ID', (type, id) => `Invalid ${type} value: ${id}`);