feat(sterni/blipqn): actually rethrow error messages in WithFlipdot

Passing a namespace as 𝕩 to •CurrentError is not allowed since it is
reserved for future use (not sure how it'll change the behavior
exactly). Since WithFlipdot always passes a namespace as 𝕩, this is a
relevant problem for blipqn. To work around it, we wrap the passed
argument in a list (and unwrap it for 𝔾).

Change-Id: I3382f754cbb64ad799e47b7d174d641c43a0f2e0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13125
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

users/sterni/blipqn/blipqn.bqn

@@ -35,7 +35,8 @@ MakeFlipdot ← {
 # the original error location, though.
 _defer_ ← {
   # can't use •CurrentError if 𝕩 is namespace: https://github.com/dzaima/cbqn/commit/d6609df82
-  s‿r ← (1⊸⋈∘𝔾)⎊(0⊸⋈∘((6⊸=•Type)◶⟨•CurrentError,"_defer_: Unknown Error occurred"˙⟩)) 𝕩 ⋄ 𝔽 𝕩 ⋄ r⊣r!s;
+  # to avoid this problem, always wrap 𝕩 in a list and unwrap it before calling 𝔾
+  s‿r ← (1⊸⋈∘𝔾∘⊑)⎊(0⊸⋈∘•CurrentError) ⋈𝕩 ⋄ 𝔽 𝕩 ⋄ r⊣r!s;
   (𝕨⊸𝔽) _𝕣_ (𝕨⊸𝔾) 𝕩
 }