Firebase Cloud Function Deployment fails with Build Error but no details - firebase

Question

After running
firebase deploy --only functions
I get this Build Error:
{
"metrics": {},
"error": {
"buildpackId": "",
"buildpackVersion": "",
"errorType": "OK",
"canonicalCode": "OK",
"errorId": "",
"errorMessage": ""
},
"stats": [
{
"buildpackId": "google.nodejs.runtime",
"buildpackVersion": "1.0.0",
"totalDurationMs": 1311,
"userDurationMs": 0
},
{
"buildpackId": "google.utils.archive-source",
"buildpackVersion": "0.0.1",
"totalDurationMs": 633,
"userDurationMs": 632
},
{
"buildpackId": "google.nodejs.npm",
"buildpackVersion": "1.0.0",
"totalDurationMs": 16330,
"userDurationMs": 15831
},
{
"buildpackId": "google.nodejs.functions-framework",
"buildpackVersion": "0.9.4",
"totalDurationMs": 8410,
"userDurationMs": 7989
},
{
"buildpackId": "google.config.entrypoint",
"buildpackVersion": "0.9.0",
"totalDurationMs": 0,
"userDurationMs": 0
},
{
"buildpackId": "google.utils.label",
"buildpackVersion": "0.0.2",
"totalDurationMs": 0,
"userDurationMs": 0
}
],
"warnings": null,
"customImage": false
}
How to tackle this? There seams no information anywhere, what is going wrong.
Update: When I try deploying a single function it works about one of ten times.
Update: Sometimes, instead of the Build Error, I get Invalid Source Token. No changes to the code. Just another try to deploy:
{
"protoPayload": {
"#type": "type.googleapis.com/google.cloud.audit.AuditLog",
"status": {
"code": 9,
"message": "Invalid source token"
},
"authenticationInfo": {
"principalEmail": "witoslaw.koczewski#gmail.com"
},
"serviceName": "cloudfunctions.googleapis.com",
"methodName": "google.cloud.functions.v1.CloudFunctionsService.UpdateFunction",
"resourceName": "projects/happygast/locations/europe-west1/functions/onWriteBenutzer"
},
"insertId": "-tykpquc6n0",
"resource": {
"type": "cloud_function",
"labels": {
"project_id": "happygast",
"region": "europe-west1",
"function_name": "onWriteBenutzer"
}
},
"timestamp": "2022-09-27T18:40:55.742542Z",
"severity": "ERROR",
"logName": "projects/happygast/logs/cloudaudit.googleapis.com%2Factivity",
"operation": {
"id": "operations/aGFwcHlnYXN0L2V1cm9wZS13ZXN0MS9vbldyaXRlQmVudXR6ZXIvWUFWMXpjUEpsYk0",
"producer": "cloudfunctions.googleapis.com",
"last": true
},
"receiveTimestamp": "2022-09-27T18:40:56.281792834Z"
}
Update: A day later the problem was gone. It seams, this was a temporary issue in the cloud.