bbox is undefined when embed TTC type font

[gjSCUT]

Here is my font:
MEIRYO.TTC.zip

When I called

pdf.embedFont(fs.readFileSync(path.resolve('fonts', 'MEIRYO.TTC')));

It throwed undefined exception:

TypeError: Cannot read property 'minX' of undefined
    at CustomFontEmbedder.<anonymous> (/home/guojun/HUE/WorkSpace/Develop/recruiting-admin-page/node_modules/pdf-lib/src/core/embedders/CustomFontEmbedder.ts:157:17)
    at step (/home/guojun/HUE/WorkSpace/Develop/recruiting-admin-page/node_modules/pdf-lib/node_modules/tslib/tslib.js:141:27)
    at Object.next (/home/guojun/HUE/WorkSpace/Develop/recruiting-admin-page/node_modules/pdf-lib/node_modules/tslib/tslib.js:122:57)
    at fulfilled (/home/guojun/HUE/WorkSpace/Develop/recruiting-admin-page/node_modules/pdf-lib/node_modules/tslib/tslib.js:112:62)

[nigamimi]

• pdf-lib is using @pdf-lib/fontkit for parsing fonts.
• type definition for fontkit is incorrect
  • d.ts says fontkit.craete() always returns Font
  • but reality it returns TrueTypeCollection when passed binary is TTC without second argument. see implementation
    • https://github.com/Hopding/pdf-lib/blob/master/src/core/embedders/CustomFontEmbedder.ts#L23-L31
    • https://github.com/foliojs/fontkit/blob/master/src/index.js#L9-L15
    • https://github.com/foliojs/fontkit/blob/master/src/base.js#L40-L51
    • https://github.com/Hopding/fontkit/blob/master/src/TrueTypeCollection.js#L21-L23
  • TrueTypeCollection does not have bbox for its member
• incorrect type definition allows incorrect codes to pass tsc.

I am not really sure that CustomFontEmbedder can embed a font if CustomFontEmbedder#for accepts an extra argument for postscriptName.
I've never tried that or don't have enough knowledge about Font program.

[Leko]

Same here on NotoSansCJK-Regular.ttc and NotoSansCJK-Bold.ttc

[Hopding]

Added this to the roadmap for tracking: #998