src/main/wacc/typeChecker.scala

@@ -159,17 +159,18 @@ object typeChecker {
       ctx.typeOf(id).satisfies(constraint, id.pos)
     case ArrayElem(id, indices) =>
       val arrayTy = ctx.typeOf(id)
-      val elemTy = indices.foldLeft(arrayTy) { (acc, elem) =>
+      val elemTy = indices.foldLeftM(arrayTy) { (acc, elem) =>
         checkValue(elem, Constraint.Is(KnownType.Int, "array index must be an int"))
         acc match {
-          case KnownType.Array(innerTy) => innerTy
-          case _ =>
+          case KnownType.Array(innerTy) => Some(innerTy)
+          case nonArrayTy =>
             ctx.error(
               Error.TypeMismatch(elem.pos, KnownType.Array(?), acc, "cannot index into a non-array")
             )
+            None
         }
       }
-      elemTy.satisfies(constraint, id.pos)
+      elemTy.getOrElse(?).satisfies(constraint, id.pos)
     case Parens(expr) => checkValue(expr, constraint)
     case l @ ArrayLiter(elems) =>
       KnownType