fix failing unit test in search-list.sml/build-search-list.sml: perform bounds checking into array

fcore/build-search-list.sml

@@ -27,7 +27,7 @@ struct
     case rightStrings of
       hd :: tl =>
         let
-          val strIdx = absIdx - bufferIdx
+          val strIdx = Int.max (0, absIdx - bufferIdx)
         in
           if strIdx < String.size hd then
             helpNextMatch (strIdx, hd, tl, absIdx, searchString, 0)

fcore/search-list.sml

@@ -226,12 +226,15 @@ struct
   fun goToNum (num, {left, right}: t) =
     case right of
       hd :: tl =>
-        if num >= Vector.sub (hd, 0) then
+        if Vector.length hd > 0 then
+          if Vector.sub (hd, 0) >= Vector.sub (hd, 0) then
             (* num is greater or equal to first el on right so go right *)
             helpGoToNumRight (num, left, right)
           else
             (* num is less than first el on right so go left *)
             helpGoToNumLeft (num, left, right)
+        else
+          helpGoToNumLeft (num, left, right)
     | [] => helpGoToNumLeft (num, left, right)
 
   fun delRightFromHere (finish, left, right) =

test/regression.sml

@@ -10,12 +10,12 @@ struct
       let
         val chr = String.sub (str, pos)
         val app = AppUpdate.update (app, InputMsg.CHAR_EVENT chr)
+                  handle _ => raise Fail (Int.toString pos)
       in
         updateLoop (pos + 1, str, app)
       end
 
-  fun updateAppWithChars (historyString, app) =
+  fun applyChars (historyString, app) = updateLoop (0, historyString, app)
-    updateLoop (0, historyString, app)
 
   fun appFromText text =
     let val buffer = LineGap.fromString text
@@ -36,8 +36,19 @@ struct
       str
     end
 
+  val initialApp = appFromText initialText
+
   val charEventTests = describe "CHAR_EVENT regressions"
-    [test "placeholder" (fn _ => Expect.isTrue true)]
+    [test "SearchList.goToNum vector bounds regression (1)" (fn _ =>
+       let
+         val app = appFromText initialText
+         val history = "G12dk"
+         val history = "100G55dkz33dk"
+         val newApp = applyChars (history, app)
+       in
+         (* just expect that we do not fail or throw an exception *)
+         Expect.isTrue true
+       end)]
 
   val tests = [charEventTests]
 end