I’m trying to write a JSON schema for a config file, so the config file object has a tasks array containing several properties, one of them being an enum “restart”.
I want my configuration to have a “restartAttempts” property only if “restart” is set to “on-failure”, so I thought I could use “if”, “then” blocks in my schema, but it turns out that it’s not working as expected, even if I provide “restart”: “on-failure”, I still get a syntax error in my lsp telling me property restartAttempts is not allowed. Here is the schema:

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "TMConfig",
  "description": "TaskMaster configuration file",
  "type": "object",
  "properties": {
    "tasks": {
      "type": "array",
      "description": "The tasks to be executed",
      "items": {
        "type": "object",
        "properties": {
          "command": {
            "type": "string",
            "description": "The executable to run"
          },
          "arguments": {
            "type": "array",
            "default": [],
            "description": "The arguments to pass to the executablenDefault is []",
            "items": {
              "type": "string"
            }
          },
          "startAtLaunch": {
            "type": "boolean",
            "default": true,
            "description": "Wether or not to start the process(es) at launchnDefault is true"
          },
          "instances": {
            "type": "number",
            "default": 1,
            "description": "The number of instances of the process to runnDefault is 1",
            "minimum": 1
          },
          "restart": {
            "enum": ["always", "never", "on-failure", "unless-stopped"],
            "default": "on-failure",
            "description": "'always': always restart the process if it exitsn'never': never restart the processn'on-failure': restart if the process exits with an error coden'unless-stopped': restart the process except if the user stops it manually through the consolenDefault is 'on-failure'"
          },
          "expectedExitStatus": {
            "type": "number",
            "default": 0,
            "description": "The expected success exit status code for the process(es)nDefault is 0"
          },
          "startTime": {
            "type": "number",
            "default": 0,
            "description": "The time to wait (in milliseconds) before considering that a process is sucessfuly startednDefault is 0",
            "minimum": 0
          },
          "stopTime": {
            "type": "number",
            "default": 5000,
            "description": "The time to wait (in milliseconds) after a graceful stop before killing a processnDefault is 5000",
            "minimum": 0
          },
          "stopSignal": {
            "enum": [
              "SIGINT",
              "SIGQUIT",
              "SIGTERM",
              "SIGUSR1",
              "SIGUSR2",
              "SIGSTOP",
              "SIGTSTP"
            ],
            "default": "SIGSTOP",
            "description": "The signal used to quit a process gracefullynDefault is 'SIGSTOP'"
          },
          "stdout": {
            "enum": ["ignore", "inherit", "redirect"],
            "default": "redirect",
            "description": "'ignore': ignore stdoutn'inherit': show stdout on taskmaster consolen'redirect': redirect stdout to a log filenDefault is 'redirect'"
          },
          "stderr": {
            "enum": ["ignore", "inherit", "redirect"],
            "default": "redirect",
            "description": "'ignore': ignore stderrn'inherit': show stderr on taskmaster consolen'redirect': redirect stderr to a log filenDefault is 'redirect'"
          },
          "logDir": {
            "type": "string",
            "default": "/var/log/taskmaster",
            "description": "The path in which to save output log filesnDefault is /var/log/taskmaster"
          },
          "environment": {
            "type": "object",
            "default": {},
            "description": "Variables to pass as environment to the process(es)nDefault is {}",
            "required": [],
            "additionalProperties": {
              "type": "string"
            }
          },
          "workingDirectory": {
            "type": "string",
            "default": ".",
            "description": "The working directorynDefault is '.'"
          },
          "permissions": {
            "type": ["number", "null"],
            "default": null,
            "description": "The permissions umask to set before launching the program, or null to leave the permissions as they arenDefault is null",
            "maximum": 777
          }
        },
        "if": {
          "properties": {
            "restart": { "const": "on-failure" }
          }
        },
        "then": {
          "properties": {
            "restartAttempts": {
              "type": "number",
              "default": 5,
              "description": "The number of restart attempts (or 0 for infinite attemps) if 'restart' is set to 'on-failure'nDefault is 5",
              "minimum": 0
            }
          }
        },
        "required": ["command"],
        "additionalProperties": false
      },
      "additionalItems": false
    }
  }
}

I’m using neovim with Mason and the jsonls lsp (vscode-json-language-server).
I checked if there was an available update in Mason / Lazy, but it seems to be up to date, but I’m doing the same as the JSON Schemas official example