`]Create <anonymous ns>`: more helpful error

[MaxCan-Code]

      ns←⎕ns''
      ns.foo←{⍵}
      ]Create ns ns
ERRORS ENCOUNTERED: ⎕SE.Link.Create: Not a properly named namespace: #.ns
    ⍝   should be
⍝ ERRORS ENCOUNTERED: ⎕SE.Link.Create: Not a properly named namespace: #.ns
⍝ try deleting #.ns then recreate #.ns like so: '#.ns'⎕ns''

[abrudz]

Or even better, suggest setting ns.⎕DF to a path that reaches it: ns.⎕DF⍕ns