[BUG] panic while creating check

__Steps to reproduce:__
Using the influx-python library

```python
ChecksService().create_check(post_check=DeadmanCheck(
level=level, every=every, status_message_template="Check: ${ r._check_name } is: ${ r._level }", name=name,
query=self.__create_dashboard_query(query=query, name=name), status=status, description=description, org_id=self.get_organization_id(), offset="0s", labels=[],
report_zero=False, stale_time="10m", tags=[])
```

The Deadman check generates the following payload
```json
{
"created_at":"None",
"description":"hooha",
"every":"10m",
"id":"None",
"labels":[

],
"last_run_error":"None",
"last_run_status":"None",
"latest_completed":"None",
"level":"WARN",
"links":"None",
"name":"test",
"offset":"0s",
"org_id":"c144bc298a525db6",
"owner_id":"None",
"query":{
"builder_config":"None",
"edit_mode":"advanced",
"name":"test",
"text":"from(bucket: \"things\") |> range(start: -7d) |> filter(fn: ""(r) => r._measurement == \"streams\") |> filter(fn: (r) => ""r.identifier == \"mbin_p4\") |> filter(fn: (r) => r._field ""== \"v\") |> filter(fn: (r) => r.mac == \"b827ebc5308a\") "
},
"report_zero":false,
"stale_time":"10m",
"status":"active",
"status_message_template":"Check: ${ r._check_name } is: ${ r._level }",
"tags":[

],
"task_id":"None",
"time_since":"None",
"type":"deadman",
"updated_at":"None"
}
```

__Expected behavior:__
Check should be created

__Actual behavior:__

__Environment info:__

* System info: Linux 5.4.0-66-generic x86_64
* InfluxDB version: InfluxDB 2.0.7 (git: 2a45f0c037) build_date: 2021-06-04T19:17:40Z
* Other relevant environment details: na

__Config:__
Copy any non-default config values here or attach the full config as a gist or file.

__Logs:__
```
ts=2021-07-06T14:00:17.507903Z lvl=error msg="a panic has occurred" log_id=0VB1kwOl000 handler=panic error="/api/v2/checks: runtime error: invalid memory address or nil pointer dereference" stacktrace="goroutine 1705 [running]:\nruntime/debug.Stack(0xc002a06e40, 0xc002acd602, 0x21f87cb)\n\t/usr/local/go/src/runtime/debug/stack.go:24 +0x9f\ngithub.com/influxdata/influxdb/v2/http.baseHandler.panic(0x3d78920, 0x34ae098, 0x3dacc40, 0xc002a38e20, 0xc000155900, 0x3983080, 0x4d043c0)\n\t/home/circleci/go/src/github.com/influxdata/influxdb/http/router.go:96 +0x21d\ngithub.com/influxdata/httprouter.(*Router).recv(0xc000628a20, 0x3dacc40, 0xc002a38e20, 0xc000155900)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/httprouter@v1.3.1-0.20191122104820-ee83e2772f69/router.go:361 +0x7b\npanic(0x3983080, 0x4d043c0)\n\t/usr/local/go/src/runtime/panic.go:969 +0x175\ngithub.com/influxdata/flux/ast.(*formatter).formatDurationLiteral(0xc002aac0b0, 0x0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:694 +0x46\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd8a00, 0x0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:803 +0x43f\ngithub.com/influxdata/flux/ast.(*formatter).formatProperty(0xc002aac0b0, 0xc002adb290)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:601 +0x110\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd92a0, 0xc002adb290)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:809 +0x25f\ngithub.com/influxdata/flux/ast.(*formatter).formatObjectExpressionBraces(0xc002aac0b0, 0xc002adb320, 0x3dd8e00)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:583 +0x1d7\ngithub.com/influxdata/flux/ast.(*formatter).formatObjectExpressionAsFunctionArgument(0xc002aac0b0, 0xc002adb320)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:545 +0x45\ngithub.com/influxdata/flux/ast.(*f
ormatter).formatCallExpression(0xc002aac0b0, 0xc002adb3b0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:491 +0x16c\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd8820, 0xc002adb3b0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:757 +0x225\ngithub.com/influxdata/flux/ast.(*formatter).formatProperty(0xc002aac0b0, 0xc002adb680)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:601 +0x110\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd92a0, 0xc002adb680)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:809 +0x25f\ngithub.com/influxdata/flux/ast.(*formatter).formatObjectExpressionBraces(0xc002aac0b0, 0xc002adb710, 0x3dd8e00)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:583 +0x1d7\ngithub.com/influxdata/flux/ast.(*formatter).formatObjectExpressionAsFunctionArgument(0xc002aac0b0, 0xc002adb710)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:545 +0x45\ngithub.com/influxdata/flux/ast.(*formatter).formatCallExpression(0xc002aac0b0, 0xc002adb7a0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:491 +0x16c\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd8820, 0xc002adb7a0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:757 +0x225\ngithub.com/influxdata/flux/ast.(*formatter).formatPipeExpression(0xc002aac0b0, 0xc002acfd60)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:506 +0x110\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd91e0, 0xc002acfd60)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:759 +0x8df\ngithub.com/influxdata/flux/ast.(*formatter).formatPipeExpression(0xc002aac0b0, 0xc002acfdb0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:501 +0x6c\ngithub.com/influxdata/f
lux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd91e0, 0xc002acfdb0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:759 +0x8df\ngithub.com/influxdata/flux/ast.(*formatter).formatExpressionStatement(0xc002aac0b0, 0xc002acfe00)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:329 +0x68\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd8a60, 0xc002acfe00)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:749 +0x7b2\ngithub.com/influxdata/flux/ast.(*formatter).formatFile(0xc002aac0b0, 0xc002a449a0, 0x0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:276 +0x1ce\ngithub.com/influxdata/flux/ast.(*formatter).formatPackage(0xc002aac0b0, 0xc002a3c770)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:234 +0xde\ngithub.com/influxdata/flux/ast.(*formatter).formatNode(0xc002aac0b0, 0x3dd9060, 0xc002a3c770)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:733 +0xb93\ngithub.com/influxdata/flux/ast.Format(0x3dd9060, 0xc002a3c770, 0x4, 0xc002a056b0)\n\t/home/circleci/go/pkg/mod/github.com/influxdata/flux@v0.117.0/ast/format.go:18 +0x66\ngithub.com/influxdata/influxdb/v2/notification/check.Deadman.GenerateFlux(0x7cb06fed598e000, 0xc002a05698, 0x4, 0xc002a056b0, 0x5, 0x73b1d3355a7c000, 0xc144bc298a525db6, 0xc001fb4870, 0xe2, 0xc002a056a0, ...)\n\t/home/circleci/go/src/github.com/influxdata/influxdb/notification/check/deadman.go:40 +0xf6\ngithub.com/influxdata/influxdb/v2/checks.(*Service).createCheckTask(0xc0052cca80, 0x3dc22c0, 0xc002a09950, 0x3deee60, 0xc002a34480, 0xc002a05710, 0x6, 0x3dc22c0, 0xc002a09950, 0x0)\n\t/home/circleci/go/src/github.com/influxdata/influxdb/checks/service.go:339 +0x66\ngithub.com/influxdata/influxdb/v2/checks.(*Service).CreateCheck(0xc0052cca80, 0x3dc22c0, 0xc002a09950, 0x3deee60, 0xc002a34480, 0xc002a05710, 0x6, 0x73b1d3355a7c000, 0x0, 0x0)\n\t/home/circleci/go/src/github.com/influxdata/influxdb
```

__Performance:__
Generate profiles with the following commands for bugs related to performance, locking, out of memory (OOM), etc.

```sh
# Commands should be run when the bug is actively happening.
# Note: This command will run for ~30 seconds.
curl -o profiles.tar.gz "http://localhost:8086/debug/pprof/all?cpu=30s"
iostat -xd 1 30 > iostat.txt
# Attach the `profiles.tar.gz` and `iostat.txt` output files.
```

Start with notification/check/deadman.go:40 and follow the create-check path through checks/service.go:339, using the reported Python payload and stack trace. Inspect the Flux formatter call involved in generating the Deadman check query. Done means creating this check no longer panics and the check is created successfully.

Written by the indexing model from the issue text.