Rework nil/option for nre in light of ""==nil

Fixes #9243

lib/impure/nre/private/util.nim

@@ -1,21 +1,9 @@
 ## INTERNAL FILE FOR USE ONLY BY nre.nim.
 import tables
 
-proc fget*[K, V](self: Table[K, V], key: K): V =
-  if self.hasKey(key):
-    return self[key]
-  else:
-    raise newException(KeyError, "Key does not exist in table: " & $key)
-
 const Ident = {'a'..'z', 'A'..'Z', '0'..'9', '_', '\128'..'\255'}
 const StartIdent = Ident - {'0'..'9'}
 
-proc checkNil(arg: string): string =
-  if arg == nil:
-    raise newException(ValueError, "Cannot use nil capture")
-  else:
-    return arg
-
 template formatStr*(howExpr, namegetter, idgetter): untyped =
   let how = howExpr
   var val = newStringOfCap(how.len)
@@ -32,7 +20,7 @@ template formatStr*(howExpr, namegetter, idgetter): untyped =
         i += 2
       elif how[i + 1] == '#':
         var id {.inject.} = lastNum
-        val.add(checkNil(idgetter))
+        val.add(idgetter)
         lastNum += 1
         i += 2
       elif how[i + 1] in {'0'..'9'}:
@@ -41,7 +29,7 @@ template formatStr*(howExpr, namegetter, idgetter): untyped =
         while i < how.len and how[i] in {'0'..'9'}:
           id += (id * 10) + (ord(how[i]) - ord('0'))
           i += 1
-        val.add(checkNil(idgetter))
+        val.add(idgetter)
         lastNum = id + 1
       elif how[i + 1] in StartIdent:
         i += 1
@@ -49,7 +37,7 @@ template formatStr*(howExpr, namegetter, idgetter): untyped =
         while i < how.len and how[i] in Ident:
           name.add(how[i])
           i += 1
-        val.add(checkNil(namegetter))
+        val.add(namegetter)
       elif how[i + 1] == '{':
         i += 2
         var name {.inject.} = ""
@@ -57,7 +45,7 @@ template formatStr*(howExpr, namegetter, idgetter): untyped =
           name.add(how[i])
           i += 1
         i += 1
-        val.add(checkNil(namegetter))
+        val.add(namegetter)
       else:
         raise newException(Exception, "Syntax error in format string at " & $i)
   val