flakey test: X cats.parse.ParserTest.a.flatMap(b) composes as expected parser00

I think this is a case of the flatMap optimization exposing a better error message (flatMap where the left is a known value is the same as a product).

==> X cats.parse.ParserTest.a.flatMap(b) composes as expected parser00  0.218s munit.ComparisonFailException: /home/runner/work/cats-parse/cats-parse/core/shared/src/test/scala/cats/parse/ParserTest.scala:1131
[318](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:318)
1130:
[319](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:319)
1131:        assertEquals(indirect, directResult)
[320](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:320)
1132:      }
[321](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:321)
values are not the same
[322](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:322)
=> Obtained
[323](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:323)
Left(
[324](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:324)
  value = Error(
[325](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:325)
    failedAtOffset = 0,
[326](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:326)
    expected = NonEmptyList(
[327](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:327)
      head = OneOfStr(
[328](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:328)
        offset = 0,
[329](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:329)
        strs = List(
[330](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:330)
          " s(\\).YYZ"
[331](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:331)
        )
[332](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:332)
      ),
[333](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:333)
      tail = List(
[334](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:334)
        InRange(
[335](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:335)
          offset = 0,
[336](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:336)
          lower = '\u0000',
[337](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:337)
          upper = '\uffff'
[338](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:338)
        )
[339](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:339)
      )
[340](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:340)
    )
[341](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:341)
  )
[342](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:342)
)
[343](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:343)
=> Diff (- obtained, + expected)
[344](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:344)
     expected = NonEmptyList(
[345](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:345)
-      head = OneOfStr(
[346](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:346)
+      head = InRange(
[347](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:347)
         offset = 0,
[348](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:348)
-        strs = List(
[349](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:349)
-          " s(\\).YYZ"
[350](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:350)
-        )
[351](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:351)
+        lower = '\u0000',
[352](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:352)
+        upper = '\uffff'
[353](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:353)
       ),
[354](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:354)
-      tail = List(
[355](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:355)
-        InRange(
[356](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:356)
-          offset = 0,
[357](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:357)
-          lower = '\u0000',
[358](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:358)
-          upper = '\uffff'
[359](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:359)
-        )
[360](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:360)
-      )
[361](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:361)
+      tail = Nil
[362](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:362)
     )
[363](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:363)

[364](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:364)
Failing seed: w7VthRO-iPVJWFY3rXtWzH4b3xVthbeUio5nWNQeoUA=
[365](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:365)
You can reproduce this failure by adding the following override to your suite:
[366](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:366)

[367](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:367)
  override val scalaCheckInitialSeed = "w7VthRO-iPVJWFY3rXtWzH4b3xVthbeUio5nWNQeoUA="
[368](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:368)

[369](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:369)
Falsified after 1104 passed tests.
[370](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:370)
> ARG_0: GenT(OneOf(List(Map(Void(AnyChar),<function1>), Map(Str( s(\).YYZ),<function1>))))
[371](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:371)
> ARG_1: ""
[372](https://github.com/typelevel/cats-parse/runs/5614705985?check_suite_focus=true#step:7:372)
> ARG_2: org.scalacheck.GenArities$$Lambda$11873/1560244765@4d07dfbe

Start with core/shared/src/test/scala/cats/parse/ParserTest.scala at line 1131 and reproduce the property failure using the reported ScalaCheck seed. Compare the indirect and direct results for a.flatMap(b), then inspect the flatMap optimization mentioned in the issue. Done means the test no longer flakes and the two results agree.