htmlfiles: Handle localStorage not accessible

In some cases, if based on the browser's settings - localStorage
is not accessible, fallback and don't save the sort-columns into
localStorage.
While the UX is a little inconvenient, at least the page doesn't
break - sorting on columns is still possible, but not retained
between pages.

CHANGES.rst

@@ -30,7 +30,13 @@ Unreleased
 
 - Windows 3.8 wheels were incorrectly built, but are now fixed. (`issue 949`_)
 
+- HTML report couldn't be sorted if localStorage wasn't available. This is now
+  fixed: sorting works even though the sorting setting isn't retained. (`issue
+  944`_ and `pull request 945`_). Thanks, Abdeali Kothari.
+
 .. _issue 943: https://github.com/nedbat/coveragepy/issues/943
+.. _issue 944: https://github.com/nedbat/coveragepy/issues/944
+.. _pull request 945: https://github.com/nedbat/coveragepy/pull/945
 .. _issue 949: https://github.com/nedbat/coveragepy/issues/949
 
 

CONTRIBUTORS.txt

@@ -4,6 +4,7 @@ extended and maintained by Ned Batchelder.
 Other contributions, including writing code, updating docs, and submitting
 useful bug reports, have been made by:
 
+Abdeali Kothari
 Adi Roiban
 Agbonze O. Jeremiah
 Albertas Agejevas

coverage/htmlfiles/coverage_html.js

@@ -172,7 +172,10 @@ coverage.index_ready = function ($) {
     // Look for a localStorage item containing previous sort settings:
     var sort_list = [];
     var storage_name = "COVERAGE_INDEX_SORT";
-    var stored_list = localStorage.getItem(storage_name);
+    var stored_list = undefined;
+    try {
+        stored_list = localStorage.getItem(storage_name);
+    } catch(err) {}
 
     if (stored_list) {
         sort_list = JSON.parse('[[' + stored_list + ']]');
@@ -222,7 +225,9 @@ coverage.index_ready = function ($) {
 
     // Watch for page unload events so we can save the final sort settings:
     $(window).unload(function () {
-        localStorage.setItem(storage_name, sort_list.toString())
+        try {
+            localStorage.setItem(storage_name, sort_list.toString())
+        } catch(err) {}
     });
 };