Hrm, the new errors highlighted some code that seems to be broken

New issue: since `Table[A, B]` allocates its backing storage with
`newSeq[KeyValuePair[A, B]]`, it's no longer legal to create a table
with `not nil` types used as either keys or values.

lib/pure/parsecsv.nim

@@ -338,8 +338,8 @@ proc rowEntry*(my: var CsvParser, entry: string): var string =
     strm.close()
 
   let index = my.headers.find(entry)
-  if index >= 0:
-    result = my.row[index]
+  assert index >= 0
+  result = my.row[index]
 
 when not defined(testing) and isMainModule:
   import os