Syntax errors no longer produce "phantom error messages"
    Generally perl will continue parsing the source code even after
    encountering a compile error. In many cases this is helpful, for
    instance with misspelled variable names it is helpful to show as many
    examples of the error as possible. But in the case of syntax errors
    continuing often produces bizarre error messages and may even cause
    segmentation faults during the compile process. In this release the
    compiler will halt at the first syntax error encountered. This means
    that any code expecting to see the specific error messages we used to
    produce will be broken. The error that is emitted will be one of the
    diagnostics that used to be produced, but in some cases some messages
    that used to be produced will no longer be displayed.

    See "Changes to Existing Diagnostics" for more details.