Avoid fatal error with invalid table data (with optional debug output)

Author: speedytwenty

src/layout-manager.js

@@ -88,14 +88,19 @@ const { ColSpanCell, RowSpanCell } = Cell;
   }
 
   function addRowSpanCells(table) {
-    table.forEach(function (row, rowIndex) {
+    table.forEach(function (row) {
       row.forEach(function (cell) {
         for (let i = 1; i < cell.rowSpan; i++) {
           let rowSpanCell = new RowSpanCell(cell);
+          const line = cell.y + i;
           rowSpanCell.x = cell.x;
-          rowSpanCell.y = cell.y + i;
+          rowSpanCell.y = line;
           rowSpanCell.colSpan = cell.colSpan;
-          insertCell(rowSpanCell, table[rowIndex + i]);
+          if (!table[line]) {
+            const { x, y } = rowSpanCell;
+            warn(`${x}-${y}: Expected empty array for row ${line - 1} (line ${line}).`);
+          }
+          insertCell(rowSpanCell, table[rowSpanCell.y] || []);
         }
       });
     });
@@ -146,7 +151,7 @@ const { ColSpanCell, RowSpanCell } = Cell;
           cell.x = opts.x;
           cell.y = opts.y;
           warn(`Missing cell at ${cell.y}-${cell.x}.`);
-          insertCell(cell, table[y]);
+          insertCell(cell, table[y] || []);
         }
       }
     }

test/issues/296-test.js

@@ -19,7 +19,7 @@ test('it should not loop infinitely with invalid table data', async () => {
 });
 
 test('it should not error on invalid table data', () => {
-  const table = new Table();
+  const table = new Table({ debug: true });
   table.push(
     [
       { content: 'A', colSpan: 2 },
@@ -28,4 +28,6 @@ test('it should not error on invalid table data', () => {
     [{ content: 'C', colSpan: 3 }]
   );
   expect(() => table.toString()).not.toThrow();
+  // This expectation can be dropped if the expectation in the code changes
+  expect(table.messages).toContain('2-2: Expected empty array for row 1 (line 2).');
 });