From 89ff89bc48ea1d6406b2ebdf0bf07a974739be34 Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Fri, 31 Jul 2020 17:11:30 +0200
Subject: [PATCH] Some more defensive programming

---
 src/main/scala/millfork/parser/MfParser.scala | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/main/scala/millfork/parser/MfParser.scala b/src/main/scala/millfork/parser/MfParser.scala
index 519e8f44..9783a27b 100644
--- a/src/main/scala/millfork/parser/MfParser.scala
+++ b/src/main/scala/millfork/parser/MfParser.scala
@@ -33,14 +33,16 @@ abstract class MfParser[T](fileId: String, input: String, currentDirectory: Stri
   def toAst: Parsed[Program] = {
     val parse = program.parse(input + "\n\n\n")
     parse match {
-      case _:Failure[_, _] =>
-        val c = input(lastPosition.cursor)
-        if (c >= 0x100 || c < 0x20 || c == '`') {
-          log.error("Invalid character U+%04X %s".format(c.toInt, Character.getName(c)), Some(lastPosition))
-          Confusables.map.get(c) match {
-            case Some(ascii) =>
-              log.info(s"Did you mean: $ascii")
-            case _ =>
+      case _: Failure[_, _] =>
+        if (lastPosition.cursor >= 0 && lastPosition.cursor < input.length) {
+          val c = input(lastPosition.cursor)
+          if (c >= 0x100 || c < 0x20 || c == '`') {
+            log.error("Invalid character U+%04X %s".format(c.toInt, Character.getName(c)), Some(lastPosition))
+            Confusables.map.get(c) match {
+              case Some(ascii) =>
+                log.info(s"Did you mean: $ascii")
+              case _ =>
+            }
           }
         }
       case _ =>