Issue loading additional files (after a file has already been loaded)

[gabrielle-ohlson]

Since pulling the most recent commit (as well as on the live visualizer website), I came across the following issue:
If I try to load a new file (file2) after having already loaded a different one (file1), the text-contents of file2 will load, but the visualization does not update to match the new file (instead shows visualization of file1 still).

Refreshing the page before loading a new file works as a quick fix, but this issue does not come up when I use an older version of the knitout-live-visualizer repo, so it seems like there's a bug in the newest commit.

[gabrielle-ohlson]

By the way, here's the console error I get when I try to load a second file:

ace.js:8983 Uncaught TypeError: Cannot read property 'splice' of null
    at EditSession.Folding.updateFoldWidgets (ace.js:8983)
    at EditSession.EventEmitter._signal (ace.js:3454)
    at EditSession.onChange (ace.js:9338)
    at Document.EventEmitter._signal (ace.js:3454)
    at Document.applyDelta (ace.js:7379)
    at Document.$splitAndapplyLargeDelta (ace.js:7402)
    at Document.applyDelta (ace.js:7375)
    at Document.insertMergedLines (ace.js:7275)
    at Document.insert (ace.js:7203)
    at Document.setValue (ace.js:7109)
Folding.updateFoldWidgets @ ace.js:8983
EventEmitter._signal @ ace.js:3454
onChange @ ace.js:9338
EventEmitter._signal @ ace.js:3454
applyDelta @ ace.js:7379
$splitAndapplyLargeDelta @ ace.js:7402
applyDelta @ ace.js:7375
insertMergedLines @ ace.js:7275
insert @ ace.js:7203
setValue @ ace.js:7109
setValue @ ace.js:12765
reader.onload @ visualizer.html:456
load (async)
readFile @ visualizer.html:444
(anonymous) @ visualizer.html:556

[gabrielle-ohlson]

@ixchow I just double-checked to see if this is an issue with the ace submodule and can confirm that it is not. (checked by replacing the ace-builds folder in a local clone of an earlier commit that doesn't have this issue with the ace folder from a clone of the newest commit. The second file still successfully loaded.)

Going to try to figure out what's going wrong with the git-bisect command, and also going to create a duplicate of the visualizer repo to try to fix this issue/make some error-checking improvements.

[gabrielle-ohlson]

@ixchow I found the first bad commit: c916906dc624bad662a230b36c45422b6e3adce6. not sure what exactly in this commit caused the issue, but going to try to figure that out now.

[gabrielle-ohlson]

update: the issue is with line 497:

knitout-live-visualizer/visualizer.html

Line 497 in 3f37d91

editor.getSession().on('change', updateKnitoutMode);

as @ixchow pointed out, this line is meant to update the visualizer to change from js->knitout (or vice versa) when a user starts writing code in the editor that is a different language than the previous file.

when line 497 is simply removed, the visualizer no longer has issues loading a new file. at first, we thought that was the only situation in which this line of code becomes problematic, but I recently tried to type into the editor with knitout after a js file was loaded, and the same console error (ace.js:8983 Uncaught TypeError: Cannot read property 'splice' of null) came up.

so in summary, looks like its a problem with ace; potential solution: add a setTimeout() (TODO: try this out)

[gabrielle-ohlson]

I think it is because ace has handling of onchange listeners that interferes with what we're trying to do with our own editor.getSession().on('change', updateKnitoutMode); listener. See the following code from ace.js:

    this.attach = function(session) {
        if (this.session)
            this.detach();

        this.session = session;
        this.onChange = this.$onChange.bind(this);

        this.session.on('change', this.onChange);
    };

    this.detach = function() {
        if (!this.session)
            return;
        this.session.removeListener('change', this.onChange);
        this.session = null;
    };

line 8014, this.session = null; might be what is causing the error, Cannot read property 'slice' of null