Bad template string refactor w/ existing template strings

[elibarzilay]

Doing a Convert to template string refactors

const a = `x` + `y` + text + "z";

to

const a = `${`x` + `y` + text}z`;

which isn't invalid but would be better to convert it to

const a = `xy${text}z`;

(There is also a point to not do the refactor at all when the author meant to split the template strings, but in that case they just won't use the refactor.)

[fatcerberus]

const a = `${`x` + `y` + text}z`;

I'm kind of surprised that works. I'd expect the backticks inside the ${} to need to be escaped.