Fix bug with extra table lines

Fixes #183

library/src/layout/table.rs

@@ -175,6 +175,10 @@ impl Layout for TableElem {
 
         // Add lines and backgrounds.
         for (frame, rows) in layout.fragment.iter_mut().zip(&layout.rows) {
+            if layout.cols.is_empty() || rows.is_empty() {
+                continue;
+            }
+
             // Render table lines.
             if let Some(stroke) = &stroke {
                 let thickness = stroke.thickness;

tests/typ/bugs/table-lines.typ

@@ -0,0 +1,10 @@
+// Ensure no empty lines before a table that doesn't fit into the first page.
+
+---
+#set page(height: 50pt)
+
+Hello
+#table(
+  columns: 4,
+  [1], [2], [3], [4]
+)