Strikethrough range incorrectly detected for multiline text

[shp7724]

The range for a multiline strikethrough is incorrectly detected when parsing a Markdown string using swift-markdown. Specifically, the detected range ends prematurely at the first line of the strikethrough block instead of spanning the entire multiline strikethrough content.

Steps to reproduce

let string = """
para1

~~this
is
multiline
strikethrough~~

para2
"""
let document = Document(parsing: string)
print(document.debugDescription(options: .printEverything))

Expected Output:

The strikethrough range should correctly span from the start of the first line to the end of the last line, i.e., from 3:1 to 6:16.

Actual Output:

The strikethrough range is detected as 3:1-3:16, which only covers the first line of the multiline strikethrough block:

Document @1:1-8:6 Root #2 #0
├─ Paragraph @1:1-1:6 #1
│  └─ Text @1:1-1:6 #2 "para1"
├─ Paragraph @3:1-6:16 #3
│  └─ Strikethrough @3:1-3:16 #4
│     ├─ Text @3:3-3:7 #5 "this"
│     ├─ SoftBreak #6
│     ├─ Text @4:1-4:3 #7 "is"
│     ├─ SoftBreak #8
│     ├─ Text @5:1-5:10 #9 "multiline"
│     ├─ SoftBreak #10
│     └─ Text @6:1-6:14 #11 "strikethrough"
└─ Paragraph @8:1-8:6 #12
   └─ Text @8:1-8:6 #13 "para2"

Strikethrough @3:1-3:16 #4

Environment:

• swift-markdown version: 0.4.0
• Xcode version: 15.4.0

Questions:

• Is this behavior from the upstreams, such as cmark-gfm?
• Can this possibly be fixed in a future release?

Related issues found:

• sourcepos broken for tables and inlines and confusing CMARK_OPT_SOURCEPOS behavior github/cmark-gfm#222
• Fix source positions for inlines. commonmark/cmark#298

Thank you for your assistance.