Remove dead code containing error. (#825)

Author: skiplabsdaniel

skiplang/prelude/src/skstore/File.sk

@@ -158,14 +158,6 @@ extension base class .Inspect {
 class VoidFile() extends File
 
 class IntFile(value: Int) extends File uses Orderable, Show {
-  fun +<T: Integral>(x: T): IntFile {
-    !this.value = this.value + x;
-    this
-  }
-  fun -<T: Integral>(x: T): IntFile {
-    !this.value = this.value + x;
-    this
-  }
   fun toString(): String {
     this.value.toString()
   }

skiplang/prelude/tests/skfs/StressTest.sk

@@ -591,7 +591,7 @@ fun updateProgram(
   i: Int,
 ): Program {
   !prog.diffs = prog.diffs.map((_, diff) ->
-    diff.map((_, arr) -> arr.map(x -> x + i))
+    diff.map((_, arr) -> arr.map(x -> SKStore.IntFile(x.value + i)))
   );
   !prog.inputs = prog.inputs.map(input -> {
     dirName = SKStore.DirName::create(input.name);

skiplang/prelude/tests/skfs/TestSubDir.sk

@@ -142,7 +142,9 @@ fun testSubSubDirUnit(): void {
       SKStore.IntFile::type,
       context,
       SKStore.DirName::create("/subDir2/"),
-      (_context, writer, key, values) ~> writer.set(key, values.first + 1),
+      (_context, writer, key, values) ~>
+        writer.set(key, SKStore.IntFile(values.first.value + 1))
+      ,
     );
     _ = dir1.map(
       SKStore.IID::keyType,