fix(annotation): Show lines/arrows when text is blank (#5560)

The compute graph refactor in #5448 dropped the `isfinite_rect` guard
that handled empty text bounding boxes. `Rect3d()` (the default for
empty strings) has Inf/-Inf origin/widths, causing `startpoint()` to
return NaN and making all annotation geometry invisible.

Closes #5557

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jkrumbiegel

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Fixed `annotation` not showing lines/arrows when `text` is blank [#5560](https://github.com/MakieOrg/Makie.jl/pull/5560)
+
 ## [0.24.9] - 2026-03-04
 
 - Added loading spinner in WGLMakie that displays while the plot is being loaded [#5469](https://github.com/MakieOrg/Makie.jl/pull/5469)

Makie/src/basic_recipes/annotation.jl

@@ -230,8 +230,10 @@ function plot!(p::Annotation)
     )
 
     # still without offset
+    # Empty strings produce non-finite Rect3d() bounding boxes, replace with zero-size rects
+    _guard_nonfinite(bb) = isfinite_rect(bb) ? bb : Rect2d(0, 0, 0, 0)
     map!(p, [txt.raw_string_boundingboxes, p.screenpoints_target], :text_bbs) do bboxes, px_pos
-        return Rect2d.(bboxes) .+ px_pos
+        return _guard_nonfinite.(Rect2d.(bboxes)) .+ px_pos
     end
 
     register_camera_matrix!(p, :data, :pixel)

ReferenceTests/src/tests/examples2d.jl

@@ -2462,6 +2462,10 @@ end
         text = "Corner", path = Ann.Paths.Corner(), labelspace = :data,
         linewidth = 3, shrink = (0, 30)
     )
+    annotation!(
+        ax, 0, -100, 10, sin(10),
+        style = Ann.Styles.LineArrow(),
+    )
 
     f
 end