wip api-v3: add error handler middleware and custom error classes

website/src/middlewares/api-v3/errorHandler.js

@@ -0,0 +1,33 @@
+'use strict';
+
+// The error handler middleware that handles all errors 
+// and respond to the client
+
+let errors = require('../../libs/api-v3/errors');
+let CustomError = errors.CustomError;
+let InternalServerError = errors.InternalServerError;
+
+module.exports = function (err, req, res, next) {
+  // TODO add logging
+  
+  // In case of a CustomError class, use it's data
+  // Otherwise try to identify the type of error (mongoose validation, mongodb unique, ...)
+  // If we can't identify it, respond with a generic 500 error
+
+  let responseErr = err instanceof CustomError ? err : null;
+
+  if (!responseErr) {
+    // Try to identify the error...
+    // ...
+    // Otherwise create an InternalServerError and use it
+    // we don't want to leak anything, just a generic error message
+    responseErr = new InternalServerError();
+  }
+
+  return res
+    .status(responseErr.httpCode)
+    .json({
+      error: responseErr.name,
+      message: responseErr.message
+    });
+};