Give error when case has an else branch even though all cases are already covered (#9930)

* Give error when case has an else branch even though all cases are already covered.
* Don't check for invalid else for type tyFloat..tyFloat128, tyString, tyError
* Remove unnecessary else in unittest.nim
* Fix sockets.nim

lib/pure/unittest.nim

@@ -239,7 +239,6 @@ method testEnded*(formatter: ConsoleOutputFormatter, testResult: TestResult) =
                     of OK: fgGreen
                     of FAILED: fgRed
                     of SKIPPED: fgYellow
-                    else: fgWhite
         styledEcho styleBright, color, prefix, "[", $testResult.status, "] ", resetStyle, testResult.testName
       else:
         rawPrint()