Describe the bug

When integrating the Yaml Language Server with Visual Studio I faced an error during the 'textDocument/completion' call to the server.
The error is outmsg = "{"jsonrpc":"2.0","id":9,"error":{"code":-32603,"message":"Request textDocument/completion failed with message: Cannot read properties of undefined (reading 'length')"}}"
The version of yaml language server is 1.10.0

I tried to attach the yaml language server nodejs process and found that the error is thrown at line 283 of this file https://github.com/redhat-developer/yaml-language-server/blob/1.10.0/src/languageservice/services/yamlCompletion.ts

I fixed this error by changing the condition to 'if (this.customTags && this.customTags.length > 0) {'
The schema is fine and gets validated with the same language server. I am happy to provide if required.

Expected Behavior

Even if customTags are not defined the completion should work successfully.

Current Behavior

It throws an error "Request textDocument/completion failed with message: Cannot read properties of undefined (reading 'length')"}}"

Steps to Reproduce

1. Setup a new VS client
2. Don't initialize the language server and start it with defaults.
3. Run the autocompletion on a schema file.

Environment

• [ yes] Windows
• Mac
• Linux
• other (please specify)