IndexError with a = a +b

[pietroppeter]

expected to work:

import bigints

var
  a = 0.initBigInt
  b = "359097073186387306".initBigInt

a = a + b  # Error: unhandled exception: index out of bounds, the container is empty [IndexError]

The above seems to work if b < uint32.high.

With a temporary variable it works:

import bigints

var
  a = 0.initBigInt
  b = "359097073186387306".initBigInt
  t: BigInt

# with a temporary variable t it works
t = a + b
a = t
echo a

for context where this came from, see https://forum.nim-lang.org/t/6327