Interpreter: BUG: data left on stack

[cyangle]

$ crystal i
Crystal interpreter 1.7.2 (2023-01-23).
EXPERIMENTAL SOFTWARE: if you find a bug, please consider opening an issue in
https://github.com/crystal-lang/crystal/issues/new/
icr:1> x : String? = "test"
BUG: data left on stack (8 bytes): Bytes[32, 156, 225, 30, 1, 0, 0, 0, 32, 156, 225, 30, 1, 0, 0, 0] (Exception)
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'raise<Exception>:NoReturn'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'raise<String>:NoReturn'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'Crystal::Repl::Interpreter#interpret<Crystal::ASTNode+, Crystal::Type+>:Crystal::Repl::Value'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'Crystal::Repl::Interpreter#interpret<Crystal::ASTNode+, Hash(String, Crystal::MetaVar)>:Crystal::Repl::Value'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'Crystal::Command#repl:(Crystal::Repl::Value | Nil)'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in '__crystal_main'
  from /usr/local/Cellar/crystal/1.7.2/libexec/crystal in 'main'
  from /usr/lib/dyld in 'start'

crystal version:

$ crystal --version
Crystal 1.7.2 (2023-01-23)

LLVM: 14.0.6
Default target: x86_64-apple-macosx