When using /title, It kept saying invalid json

Put the summary of the bug you're having here

*What I expected to happen was...:
It was supposed to put the title on the screen*
Describe what you thought should happen here

*What actually happened was...:
It kept saying "invalid json: UseJsonreader.setLenient(true)to accept malformed json at line 1 column 1"
Describe what happened here

Steps to Reproduce:
1. /title Player title "hello"
2. Read what it says
3. Wonder if I did it wrong...