table_helpers: Fix issue with empty tables

spec/support/table_helpers/table_representer.rb

@@ -102,7 +102,7 @@ def column_widths
           else
             values = tables_data.flat_map { _1.values_for_attribute(column.attribute) }
             values_max_size = values.map { column.format(_1).size }.max
-            [column.title.size, values_max_size].max
+            [column.title.size, values_max_size].compact.max
           end
         end
     end

spec/support_spec/table_helpers/table_representer_spec.rb

@@ -68,6 +68,19 @@ module TableHelpers
       end
     end
 
+    context "when there are no work packages" do
+      let(:table_data) do
+        TableData.from_work_packages([], columns)
+      end
+      let(:columns) { [Column.for("subject")] }
+
+      it "renders no rows" do
+        expect(representer.render(table_data)).to eq <<~TABLE
+          | subject |
+        TABLE
+      end
+    end
+
     describe "subject column" do
       let(:columns) { [Column.for("subject")] }
 
@@ -131,6 +144,18 @@ module TableHelpers
         TABLE
       end
 
+      context "when there are no work packages" do
+        let(:table_data) do
+          TableData.from_work_packages([], columns)
+        end
+
+        it "renders no rows" do
+          expect(representer.render(table_data)).to eq <<~TABLE
+            | MTWTFSS |
+          TABLE
+        end
+      end
+
       context "when non working days are defined" do
         let(:table) do
           <<~TABLE