${{hello:-abc}} Mismatch in parsing after upgrade

- v1.3.0 ${{hello:-abc}} == abc
- v1.4.2 ${{hello:-abc}} == abc}

The issue describes a parsing mismatch for the shell parameter expansion syntax ${{hello:-abc}} between versions 1.3.0 and 1.4.2. Start by examining the parsing logic in the codebase, likely in files handling variable substitution. Look for changes in the lexer or parser between these versions. Run existing tests to see the current behavior and write a test to reproduce the mismatch. Understanding the expected output (whether it should be 'abc' or 'abc}') is key.

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