WP5 "convert to blocks" doesn't correctly initialize pp_gallery shortcode into a block

[postmastersteve]

I had a blog post that was built in the old WP editor. It had a gallery shortcode [pp_gallery id="229"] before a couple paragraphs of text.

When converting to blocks, WordPress correctly parsed the shortcode into a new P7 gallery block followed by two paragraph blocks, but the new gallery block had a few problems:

• it renders as an empty ProPhoto block.
• the gallery selector in the right pane showed no gallery selected.
• the style selector in the right pane showed the "Full Size Images" style preselected, even though the gallery shortcode had no style associated in the shortcode. (it should initialize the control with "none selected" instead)
• after choosing my gallery, the block rendered with a style that didn't match the "Full Size Images" selection shown in the right pane - it showed in a slider appearance with arrows.
• I toggled the Style selector to my "Carousel" style and then toggled it back to "Full Size Images" - the gallery block updated each time with the proper appearance applied in the UI.
• after saving the post and refreshing the editor, I found that I could no longer change the gallery style to anything else - every time I selected a different style it did nothing and remained set to "Full Size Images" and the browser spit out a fun console error:

  Uncaught RangeError: Maximum call stack size exceeded
  at String.valueOf (<anonymous>)
  at pe (bundle.gutenberg.js?ver=7.7.6:1)
  at Tt.get (bundle.gutenberg.js?ver=7.7.6:1)
  at t.get (bundle.gutenberg.js?ver=7.7.6:1)
  at M (bundle.gutenberg.js?ver=7.7.6:12)
  at M (bundle.gutenberg.js?ver=7.7.6:12)...

  

Throughout these tests my P7 design had no gallery style set as a default, so perhaps that is a failure mode we need to investigate. But after setting a default gallery style and returning to the editor, I still couldn't alter the style of the gallery block in my post.

[postmastersteve]

UPDATE: after selecting a default gallery style in my P7 design, the style selector initializes with the design default pre-selected, which seems better... so it is really just when there is no default gallery style chosen that we fall back to inserting as Full Size Images, but we still need to fix the block so it actually renders that way instead of a hard-coded fallback slider gallery style.