Capturer destructor asserts due to bad expression parsing

[amensel]

The following asserts:

TEST_CASE("Explodes")
{
    int a = 1;
    int b = 2;
    CAPTURE(a + b);
    REQUIRE(false);
}

The following does not:

TEST_CASE("Works")
{
    int a = 1;
    int b = 2;
    CAPTURE(a+b);
    REQUIRE(false);
}

The assertion that fires:
https://github.com/catchorg/Catch2/blame/1cdaa48a0b20e28ee32553070700b86557f9619d/include/internal/catch_message.cpp#L79

The issue appears to have been caused here: https://github.com/catchorg/Catch2/blame/1cdaa48a0b20e28ee32553070700b86557f9619d/include/internal/catch_message.cpp#L66

[vector-of-bool]

Looks like you'd want to only count , instead of all whitespace as an argument delimiter, and also only when , appears at the top level (not nested within [], {}, or ()). You can count the nesting depth of each bracket type in one variable since mismatching brackets would cause the compilation to fail anyway.