Obtuse error message

[rrthomas]

The following code:

let a = fn(k, x1, x2, x3, x4, x5) {
  var m = k
  m = m - 1
}

gives this error:

ursa: Error: Line 1, col 9:
> 1 | let a = fn(k, x1, x2, x3, x4, x5) {
              ^
  2 |   var m = k
Expected "(", a block, a list, an identifier, an object, a map, a number, a literal string, a string, a boolean, "null", "-", "+", "~", "not", "launch", "yield", "await", "for", "loop", or "if"

This is unfortunate, as the real problem is that the line m = m - 1 should be m := m - 1.