Using PostgreSQL version 16.6 and its corresponding age version 1.5.0, importing a database using a CSV file is not possible when there is only one attribute in the CSV file

**Describe the bug**
Using PostgreSQL version 16.6 and its corresponding age version 1.5.0, importing a database using a CSV file is not possible when there is only one attribute in the CSV file

**How are you accessing AGE (Command line, driver, etc.)?**
- psql

**What data setup do we need to do?**
```pgsql
...
select load_labels_from_file('livejournal','Person','/import/ljournal-vertex.csv');
...
```

**What is the command that caused the error?**
```pgsql
select load_edges_from_file('livejournal','Knows9','/import/test1.csv');
SELECT * FROM cypher('livejournal', $$MATCH(a)-[r:Knows9]->(b) RETURN r $$) as (a agtype);
```
```
{"id": 4222124650659851, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {}}::edge
{"id": 4222124650659850, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {}}::edge
{"id": 4222124650659849, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {}}::edge
```

**Expected behavior**
{"id": 4222124650659855, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {"string": "John Smith"}}::edge
{"id": 4222124650659854, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {"string": "John"}}::edge
{"id": 4222124650659853, "label": "Knows9", "end_id": 844424930131969, "start_id": 844424930131969, "properties": {"string": "John Smith"}}::edge