Invalid auto-complete when `const` is an object

Describe the bug

When the value of const is an object, the auto-complete for the property/instance is garbled and invalid.

Instead of:

foo:
  bar: baz

It auto-completes as:

foo: 
  bar}: ${2:baz

Expected Behavior

Auto-complete for constant values should insert correctly, even when the constant is an object, as it does when the constant is an array, string, number, or null.

Current Behavior

Auto-complete inserts what appears to be a broken internal string.

Steps to Reproduce

1. Define a test schema as test.schema.json:

   {
       "$schema": "https://json-schema.org/draft/2020-12/schema",
       "title": "Schema with an object constant",
       "description": "Defines a schema with an object constant.",
       "type": "object",
       "properties": {
           "foo": {
               "title": "Property with an object constant",
               "const": {
                   "bar": "baz"
               }
           }
       }
   }
   

2. Define a test instance using that schema as test.instance.yaml:

   # yaml-language-server: $schema=test.schema.json
   

3. Type foo, wait for IntelliSense, then press enter.

4. Result:

   # yaml-language-server: $schema=test.schema.yaml
   foo: 
     bar}: ${2:baz
   

5. Define a test instance as test.schema.json

   {
       "$schema": "test.schema.json"
   }
   

6. Add a comma, then use IntelliSense to find the foo property and press enter to auto-complete.

7. Result:

      {
       "$schema": "test.schema.json",
       "foo": {
           "bar": "baz"
       }
   }
   

Environment

• Windows
• Mac
• Linux
• other (please specify)

Reproduce the issue with test.schema.json and test.instance.yaml, using IntelliSense on the foo property with an object const. Trace the autocomplete handling for object constants and compare it with the documented array, string, number, and null cases. Done means both YAML and JSON insert valid object values without malformed snippet placeholders.