Failed to upload generator

When trying to push local changes to Polygon, almost everything works except for generator and tests:

```
┌─ Step 8: Uploading Generators
⚠️ Failed to upload generator: gen
ℹ Uploaded 0 generator(s)
└─ ✓ Generators uploaded

┌─ Step 11: Uploading Testsets and Tests
✖ Polygon API Error: source: gen: use source file name without extension
✖ Polygon API Error: testInput: Field should not be empty
ℹ Uploaded 2 manual test(s)
ℹ Total tests configured: 3
└─ ✓ Testsets uploaded
```

The configuration im using is almost the same as in `TUTORIAL.md`:
```
"generators": [
{
"name": "gen",
"source": "./generators/gen.cpp"
}
],
"testsets": [
{
"name": "tests",
"generatorScript": {
"commands": [
{
"useInStatements": true,
"type": "manual",
"manualFile": "./manual/tests/sample1.txt",
"group": "samples"
},
{
"useInStatements": true,
"type": "manual",
"manualFile": "./manual/tests/sample2.txt",
"group": "samples"
},
{
"type": "generator",
"generator": "gen",
"range": [
1,
10
],
"group": "main"
}
]
},
"groupsEnabled": true,
"groups": [
{
"name": "samples"
},
{
"name": "main"
}
]
}
]
```

Of course, when running `polyman verify` everything works