matcher is failing

Hello. I have a conditional clause in my Groovy script that attempts to
parse a date pattern of this form: 06-14-2023. It fails - I believe in the
matcher.

I am running from a NiFi ExecuteScript processor. Here is my conditional:

              } else if ( candidate =~
/^(?:0?[1-9]|[12]\d|3[01])[\\\-\\\/]+(\d{2}|\d{1})[\\\-\\\/]+(\d{4}|\d{2})$/
) {

              log.error("BINGO!")

              matcher = candidate =~
/^(?:0?[1-9]|[12]\d|3[01])[\\\-\\\/]+(\d{2}|\d{1})[\\\-\\\/]+(\d{4}|\d{2})$/
              log.error("Matcher: ${matcher.toString()}")
              log.error("Matched substring: ${matchedSubstring}")
              day = matchedSubstring[matcher[0][1]]
              month = matchedSubstring[matcher[0][2]]
              year = matcherSubstriong[matcher[0][3]]

              log.error("Day: ${day}")
              log.error("Month: ${month}")
              log.error("Year: ${year}")

              log.error("Length of Day: ${day.length()}")
              log.error("Length of Month: ${month.length()}")
              log.error("Length of Year: ${year.length()}")

           }

My log output tells me I make it into the conditional, but then I fail on
the matcher:

2023-07-09 15:52:23,547 ERROR [Timer-Driven Process Thread-2]
o.a.nifi.processors.script.ExecuteScript
ExecuteScript[id=33a5179c-1df4-128b-52be-aaa96b947012] Candidate: 06-14-2023
2023-07-09 15:52:23,547 ERROR [Timer-Driven Process Thread-2]
o.a.nifi.processors.script.ExecuteScript
ExecuteScript[id=33a5179c-1df4-128b-52be-aaa96b947012] BINGO!
2023-07-09 15:52:23,547 ERROR [Timer-Driven Process Thread-2]
o.a.nifi.processors.script.ExecuteScript
ExecuteScript[id=33a5179c-1df4-128b-52be-aaa96b947012] Matcher:
java.util.regex.Matcher[pattern=^(?:0?[1-9]|[12]\d|3[01])[\\\-\\/]+(\d{2}|\d{1})[\\\-\\/]+(\d{4}|\d{2})$
region=0,10 lastmatch=]
2023-07-09 15:52:23,547 ERROR [Timer-Driven Process Thread-2]
o.a.nifi.processors.script.ExecuteScript
ExecuteScript[id=33a5179c-1df4-128b-52be-aaa96b947012] Matched substring:
*null*
2023-07-09 15:52:23,547 ERROR [Timer-Driven Process Thread-2]
o.a.nifi.processors.script.ExecuteScript
ExecuteScript[id=33a5179c-1df4-128b-52be-aaa96b947012] Could not parse:
06-14-2023

Can anyone help me get this matcher to work?

Thanks in advance for any help.

Jim