fix: user should not crash if email is missing

lib/db/context-field-store.js

@@ -41,7 +41,7 @@ class ContextFieldStore {
     }
 
     async _createFromConfig(customContextFields) {
-        if (customContextFields) {
+        if (customContextFields && customContextFields.length > 0) {
             this.logger.info(
                 'Create custom context fields',
                 customContextFields,

lib/user.js

@@ -24,7 +24,13 @@ module.exports = class User {
         this.email = email;
         this.systemId = systemId;
         this.permissions = permissions;
-        this.imageUrl =
-            imageUrl || gravatarUrl(email, { size: '42', default: 'retro' });
+        this.imageUrl = imageUrl || this.generateImageUrl();
+    }
+
+    generateImageUrl() {
+        return gravatarUrl(this.email || this.username, {
+            size: '42',
+            default: 'retro',
+        });
     }
 };

lib/user.test.js

@@ -57,3 +57,12 @@ test('Should require valid email', t => {
 
     t.is(error.message, 'Email "value" must be a valid email');
 });
+
+test('Should create user with only username defined', t => {
+    const user = new User({ username: 'some-user' });
+    t.is(user.username, 'some-user');
+    t.is(
+        user.imageUrl,
+        'https://gravatar.com/avatar/140fd5a002fb8d728a9848f8c9fcea2a?size=42&default=retro',
+    );
+});