fixes nim-lang/nimsuggest#76 (#10093)

* nimsuggest: prevent out-of-bound access

* fixes nim-lang/nimsuggest#76

* undo tester changes

nimsuggest/tests/ttype_highlight.nim

@@ -0,0 +1,28 @@
+type
+  TypeA = int
+  TypeB* = int
+  TypeC {.unchecked.} = array[1, int]
+  TypeD[T] = T
+  TypeE* {.unchecked.} = array[0, int]#[!]#
+
+discard """
+disabled:true
+$nimsuggest --tester $file
+>highlight $1
+highlight;;skType;;2;;2;;5
+highlight;;skType;;3;;2;;5
+highlight;;skType;;4;;2;;5
+highlight;;skType;;5;;2;;5
+highlight;;skType;;6;;2;;5
+highlight;;skType;;2;;10;;3
+highlight;;skType;;3;;11;;3
+highlight;;skType;;4;;24;;5
+highlight;;skType;;4;;33;;3
+highlight;;skType;;5;;13;;1
+highlight;;skType;;6;;25;;5
+highlight;;skType;;6;;34;;3
+highlight;;skType;;2;;10;;3
+highlight;;skType;;3;;11;;3
+highlight;;skType;;4;;33;;3
+highlight;;skType;;6;;34;;3
+"""