Ticket test: #10042

Case 1: colspan is 0

1. Click "Insert invalid cell with colspan 0" button.

Expected:

• No errors.
• Table should be inserted properly.
• Editor should not freeze.
• Inserted table cell should have no colspan attribute

Case 2: colspan is string

1. Click "Insert invalid cell with colspan "abc"" button.

Expected:

• No errors.
• Table should be inserted properly.
• Editor should not freeze.
• Inserted table cell should have no colspan attribute

Case 3: negative colspan and rowspan

1. Click "Insert invalid cell with negative colspan and rowspan" button.

Expected:

• No errors.
• Table should be inserted properly.
• Editor should not freeze.
• Inserted table cell should have no colspan or rowspan attributes