bug: json input not validated correctly

[sentry-io]

The json input is not validated to be an object, so it is possible that it is parsed to return an integer. This causes an error because it is not possible to check if a string is 'in' an integer.

Sentry Issue: MESSAGE-MANAGER-BOT-4

TypeError: argument of type 'int' is not iterable
  File "discord/ext/commands/core.py", line 85, in wrapped
    ret = await coro(*args, **kwargs)
  File "/home/admin/bot/message-bot/cogs/messages.py", line 771, in send_json_embed
    if "embeds" in dict_content or "content" in dict_content:

CommandInvokeError: Command raised an exception: TypeError: argument of type 'int' is not iterable
  File "discord/ext/commands/bot.py", line 939, in invoke
    await ctx.command.invoke(ctx)
  File "discord/ext/commands/core.py", line 863, in invoke
    await injected(*ctx.args, **ctx.kwargs)
  File "discord/ext/commands/core.py", line 94, in wrapped
    raise CommandInvokeError(exc) from exc

Ignoring exception in command send-embed-json: