XO0156: `${` without a matching `}` in the same string

Inside a string, ${ starts an interpolated expression that must be closed by } before the string ends. If a literal ${ is meant, escape the dollar sign: \${. A $ not followed by { is always literal. See core 1.6.

Example

fn f(b: Int) -> Str {
  "a ${b"
}

Fix

fn f(b: Int) -> Str {
  "a ${b}"
}

Run xo explain XO0156 for this text in a terminal, or see section 10.6 of the specification.