LoadError: cannot load such file -- parser/lexer

[native-api]

cannot load such file -- parser/lexer (LoadError)

You need to install a release of parser from RubyGems, not a checkout from Github.

Clean the cache and check where Bundler is installing it from with bundle --verbose.

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A tiny Go code fails only on Travis CI for Linux

If something works locally but not in Travis, there are differences between your local environment and Travis. Find out what this error message means and dig from there – only that can tell what the cause is and point to the discrepancy.