[Bug]: Regular expression with toJson method panics

[TharmiganK]

Description

The toJson method is allowed in anydata types where a non-json types are converted to a respective json compatible types according to the method definition:

# This does a deep copy of parameter `v` converting values that do
# not belong to json into values that do.
# A value of type `xml` is converted into a string as if
# by the `toString` function.
# A value of type `table` is converted into a list of
# mappings one for each row.
# The inherent type of arrays in the return value will be
# `json[]` and of mappings will be `map<json>`.
# A new copy is made of all structural values, including
# immutable values.

But the regexp:RegExp with toJson method panics at runtime:

error: {ballerina/lang.value}ConversionError {"message":"'anydata & readonly' value cannot be converted to 'json'"}
        at ballerina.lang.value.0:toJson(value.bal:262)
           sample:main(sample.bal:7)

The method description should be updated if this is the correct behaviour or the method should return a json value

Steps to Reproduce

• Simple regular expression with toJson

import ballerina/io;
import ballerina/lang.regexp;

regexp:RegExp regExp = re `a`;

public function main() {
    io:println(regExp.toJson());
}

• Regular expression as a record field and record with toJson

import ballerina/io;
import ballerina/lang.regexp;

regexp:RegExp regExp = re `a`;

type Rec record {
    xml xmlValue;
    table<map<string>> tableValue;
};

public function main() {
    Rec rec = {
        xmlValue: xml `<name>John</name>`,
        tableValue: table [{"key": "value"}]
    };
    io:println(rec.toJson());

    rec["regExpValue"] = regExp;
    io:println(rec.toJson());
}

Affected Version(s)

Ballerina SwanLake Update 10(2201.10.x)

OS, DB, other environment details and versions

No response

Related area

-> Runtime

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[MaryamZi]

Related to #42070.