Syserror should contain the error message when process exits with error

Currently when an exec doc causes an error there is nothing in syserror. Output contains the entire output of the run, including things that ran successfully. This would allow for more accurate automated testing and resolution.

Syserror should contain the essential information, for example:

```
az network vnet create --resource-group $RESOURCE_GROUP_NAME_ED372 \
--name $VNET_NAME_ED372 \
--address-prefix $VNET_ADDRESS_SPACE_ED372 \
--location $REGION_ED372

Expected output does not match actual output.
Got:
{
"newVNet": {
"addressSpace": {
"addressPrefixes": [
"10.1.0.0/16"
]
},
"enableDdosProtection": false,
"etag": "W/\"f2d5e05d-7ebb-4d47-8f4b-5f3366d679bf\"",
"id": "/subscriptions/f7a60fca-9977-4899-b907-005a076adbb6/resourceGroups/ExampleRG_edae6b/providers/Microsoft.Network/virtualNetworks/ExampleVNet_edae6b",
"location": "eastus",
"name": "ExampleVNet_edae6b",
"privateEndpointVNetPolicies": "Disabled",
"provisioningState": "Succeeded",
"resourceGroup": "ExampleRG_edae6b",
"resourceGuid": "xxxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
"subnets": [],
"type": "Microsoft.Network/virtualNetworks",
"virtualNetworkPeerings": []
}
}

Expected:
{
"newVNet": {
"id": "/subscriptions/xxxxx-xxxxx-xxxxx-xxxxx/resourceGroups/ExampleRG_abc123/providers/Microsoft.Network/virtualNetworks/ExampleVNet_abc123",
"location": "eastus",
"name": "ExampleVNet_abc123",
"properties": {
"addressSpace": {
"addressPrefixes": [
"10.1.0.0/16"
]
},
"provisioningState": "Succeeded"
},
"tags": null
}
}

Expected Score:0.800000
Actual Score:0.641925
```