(F) When compiling a regex pattern, an unresolved named character or sequence
was encountered. This can happen in any of several ways that bypass the lexer,
-such as using single-quotish context:
+such as using single-quotish context, or an extra backslash in double quotish:
$re = '\N{SPACE}'; # Wrong!
+ $re = "\\N{SPACE}"; # Wrong!
/$re/;
-Instead, use double-quotes:
+Instead, use double-quotes with a single backslash:
$re = "\N{SPACE}"; # ok
/$re/;