Don't pass redundant label names to table_width and list_start (#1160)

macros/asserts.asm

@@ -1,13 +1,29 @@
 ; Macros to verify assumptions about the data or code
 
+MACRO _redef_current_label
+	if DEF(\1)
+		PURGE \1
+	endc
+	if _NARG == 3 + (\3)
+		DEF \1 EQUS "\<_NARG>"
+	elif DEF(..)
+		if .. - @ == 0
+			DEF \1 EQUS "{..}"
+		endc
+	elif DEF(.)
+		if . - @ == 0
+			DEF \1 EQUS "{.}"
+		endc
+	endc
+	if !DEF(\1)
+		DEF \1 EQUS \2
+		{\1}:
+	endc
+ENDM
+
 MACRO table_width
 	DEF CURRENT_TABLE_WIDTH = \1
-	if _NARG == 2
-		REDEF CURRENT_TABLE_START EQUS "\2"
-	else
-		REDEF CURRENT_TABLE_START EQUS "._table_width\@"
-	{CURRENT_TABLE_START}:
-	endc
+	_redef_current_label CURRENT_TABLE_START, "._table_width\@", 2, \#
 ENDM
 
 MACRO assert_table_length
@@ -18,12 +34,7 @@ ENDM
 
 MACRO list_start
 	DEF list_index = 0
-	if _NARG == 1
-		REDEF CURRENT_LIST_START EQUS "\1"
-	else
-		REDEF CURRENT_LIST_START EQUS "._list_start\@"
-	{CURRENT_LIST_START}:
-	endc
+	_redef_current_label CURRENT_LIST_START, "._list_start\@", 1, \#
 ENDM
 
 MACRO li