Parsing font with potentially faulty GDEF table

[JonasGruenwald]

Hello, big fan of the package here!

I've got an issue that's maybe more of a question, not a bug in the package itself:

I'm trying to parse a font file and opentype.js is throwing this error:

opentype.js/src/tables/gdef.mjs

Line 49 in aa8ad76

'Unsupported GDEF table version.');

Now if I add the parsed tableVersion to the logged error message there, it's showing a value of 0.
It seems that something in the font file is incorrect, as that appears to not be a valid version for the GDEF table according to the spec I could find.

Now my thing is, I'd still like to parse that font file even though it has this inconsistency. I've added a local patch to my project as a workaround:

--- a/dist/opentype.js
+++ b/dist/opentype.js
@@ -13820,8 +13820,10 @@
 	    start = start || 0;
 	    var p = new Parser(data, start);
 	    var tableVersion = p.parseVersion(1);
-	    check.argument(tableVersion === 1 || tableVersion === 1.2 || tableVersion === 1.3,
-	        'Unsupported GDEF table version.');
+	    if(!(tableVersion === 1 || tableVersion === 1.2 || tableVersion === 1.3)){
+        console.warn(`Unsupported GDEF table version: ${tableVersion}, not parsing table!`);
+        return undefined;
+      }
 	    var gdef = {
 	        version: tableVersion,
 	        classDef: p.parsePointer(Parser.classDef),

Also worth noting that any other software seems to be able to open the font file just fine, and FontForge for example does not report any issues when loading the font.

My questions are:

Would some form of fault tolerant parsing be in scope for opentype.js?
Would contributions along those lines be welcome?
Or does the project generally only aim to be able to parse files that 100% adhere to the spec?

[Connum]

I see you've closed the issue after receiving no response - I thought I had answered, but obviously I haven't! A more graceful approach to parsing has been implemented in this PR: #704 However, development and other contribution like reviewing has apparently come to a halt in the past few months.

[JonasGruenwald]

@Connum Oh that's really cool to see, great work on this PR!
Yes I closed the issue because my personal need for this disappeared and I thought it better to not overwhelm the maintainers with irrelevant issues since there's probably a lot of other stuff to do