Parsing error with extglob inside a pattern with some special prefixes

[folliehiyuki]

An example with an asterisk at the start of the pattern:

if [[ "README.md" == *.@(md|mkd|markdown) ]]; then
    echo "This is a Markdown file"
fi

The corresponding node tree:

(if_statement) ; [1:1 - 3:2]
 condition: (test_command) ; [1:4 - 44]
  (binary_expression) ; [1:7 - 41]
   left: (string) ; [1:7 - 17]
    (string_content) ; [1:8 - 16]
   (ERROR) ; [1:22 - 24]
    (word) ; [1:22 - 24]
   right: (parenthesized_expression) ; [1:25 - 41]
    (binary_expression) ; [1:26 - 40]
     left: (binary_expression) ; [1:26 - 31]
      left: (word) ; [1:26 - 27]
      right: (word) ; [1:29 - 31]
     right: (word) ; [1:33 - 40]
 (command) ; [2:5 - 34]
  name: (command_name) ; [2:5 - 8]
   (word) ; [2:5 - 8]
  argument: (string) ; [2:10 - 34]
   (string_content) ; [2:11 - 33]

A few more examples that also produce errors:

# Start with a question mark
[[ "a.md" == ?.@(md|mkd) ]]

# Start with a dot
[[ ".md" == .@(md|mkd) ]]

# The pattern also have quoted string at the start
[[ "ab.md" == "ab".@(md|mkd) ]]

These are all valid Bash, according to https://www.gnu.org/software/bash/manual/html_node/Pattern-Matching.html