Why do I get Duplicate object key and End of file expected JSON?

I am trying to create a schema that validates coordinates depending on the system I am using: Polar, Cartesian or Cylindrical coordinates. My idea was to use an if statement to validate the used coordinates values according to the system used. The

{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"minItems": 3,
"maxItems": 3,
"items": 
{
    "system": 
    {
        "enum": ["Cartesian", "Cylindric","Spherical"],
        "description": "The type of the system"
     },
        "if":
        {
            "items": 
            {
                "system":
                {
                    "const": "Cartesian"
                }
            }
        },

        "then": 
        {
            "items":
            {
                "x": 
                {
                    "type": "number"
                },
                "y": 
                {
                    "type": "number"
                 },
                "z": 
                {
                    "type": "number"
                }     
            },
            "required": ["x","y","z"] 
        } ,
        "if":
        {
            "items": 
            {
                "system":
                {
                "const": "Spherical"
                }
             }
        },
        "then": 
         {
            "items":
            {
                "r": 
                {
                    "type": "number"
                },
                "theta":
                {
                    "type": "number",
                    "minimum": "0",
                    "maximum": "360"
                },
                "phi":
                {
                    "type": "number",
                    "minimum": "0",
                    "maximum": "180"
                }
            },
            "required": ["x","y","z"]
        },
        "if":
        {
            "items": 
            {
                "system":
                {
                    "const": "Cylindrical"
                }
            }
        },
        "then": 
        {
            "items":
            {
                "r": 
                {
                    "type": "number"
                },
                "theta":
                {
                    "type": "number",
                    "minimum": "0",
                    "maximum": "360"
                },
                "z":
                {
                    "type": "number"
                }
            },
            "required": ["x","y","z"]
        }
    }
}

}

In the end I get the following errors:

• End of file expected
• Duplicate object key

Since I am new to JSON can someone please explain what I am missing here?