From 44d99733c63f33c85e97a8edce3d50c8ba192846 Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Thu, 30 Sep 2021 13:39:02 -0400
Subject: [PATCH] Changeset: Check `.hasNext()` before calling `.next()`

---
 src/node/utils/padDiff.js        | 4 ++--
 src/static/js/Changeset.js       | 4 +++-
 src/static/js/linestylefilter.js | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/node/utils/padDiff.js b/src/node/utils/padDiff.js
index fa612c7c2..900a452c7 100644
--- a/src/node/utils/padDiff.js
+++ b/src/node/utils/padDiff.js
@@ -286,7 +286,7 @@ PadDiff.prototype._createDeletionChangeset = function (cs, startAText, apool) {
       curLineOpIterLine = curLine;
       let indexIntoLine = 0;
       let done = false;
-      while (!done) {
+      while (!done && curLineOpIter.hasNext()) {
         curLineNextOp = curLineOpIter.next();
         if (indexIntoLine + curLineNextOp.chars >= curChar) {
           curLineNextOp.chars -= (curChar - indexIntoLine);
@@ -307,7 +307,7 @@ PadDiff.prototype._createDeletionChangeset = function (cs, startAText, apool) {
       }
 
       if (!curLineNextOp.chars) {
-        curLineNextOp = curLineOpIter.next();
+        curLineNextOp = curLineOpIter.hasNext() ? curLineOpIter.next() : Changeset.newOp();
       }
 
       const charsToUse = Math.min(numChars, curLineNextOp.chars);
diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index ead0e97a9..07e17e5b7 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -2072,7 +2072,9 @@ exports.inverse = (cs, lines, alines, pool) => {
         curLineNextOp.chars = 0;
         curLineOpIter = exports.opIterator(alinesGet(curLine));
       }
-      if (!curLineNextOp.chars) curLineNextOp = curLineOpIter.next();
+      if (!curLineNextOp.chars) {
+        curLineNextOp = curLineOpIter.hasNext() ? curLineOpIter.next() : exports.newOp();
+      }
       const charsToUse = Math.min(numChars, curLineNextOp.chars);
       func(charsToUse, curLineNextOp.attribs, charsToUse === curLineNextOp.chars &&
           curLineNextOp.lines > 0);
diff --git a/src/static/js/linestylefilter.js b/src/static/js/linestylefilter.js
index ac8df82f4..84668ea46 100644
--- a/src/static/js/linestylefilter.js
+++ b/src/static/js/linestylefilter.js
@@ -108,7 +108,7 @@ linestylefilter.getLineStyleFilter = (lineLength, aline, textAndClassFunc, apool
     let nextOp, nextOpClasses;
 
     const goNextOp = () => {
-      nextOp = attributionIter.next();
+      nextOp = attributionIter.hasNext() ? attributionIter.next() : Changeset.newOp();
       nextOpClasses = (nextOp.opcode && attribsToClasses(nextOp.attribs));
     };
     goNextOp();