on_demand api's exit when provider empties rather than when relying api's are finished

[tkmcmaster]

Describe the bug

The test exits early (with no message as to why) when a provider runs out to an on_demand api.

Expected behavior

The test should continue to run until non-on_demand api calls can't get data. Also, it should log why it exited early (provider ran out)

Config file

vars:
  port: ${PORT}
load_pattern:
  - linear:
      from: 100%
      to: 100%
      over: 5m
config:
  client:
    headers:
      Accept: 'application/json'
  general:
    bucket_size: 1m
    log_provider_stats: 1m
providers:
  counterProvider:
    range:
      start: 1
      end: 10
      repeat: false
  response1:
    response: {}
  response2:
    response: {}
endpoints:
  - method: GET
    url: 'http://localhost:${port}?count=${counterProvider}'
    on_demand: true
    peak_load: 60hpm
    provides:
      response1:
        select: counterProvider
        where: response.status <= 300
        send: force
  - method: GET
    url: 'http://localhost:${port}?count=${response1}'
    on_demand: true
    peak_load: 60hpm
    provides:
      response2:
        select: response1
        where: response.status <= 300
        send: force
  - method: GET
    url: 'http://localhost:${port}?count=${response2}'
    peak_load: 60hpm

Command to run

$ PORT=8085 pewpew run ProviderEndsEarly.yaml

System info

• Operating System: Windows 10
• Pewpew version: 5.7 and 5.8 preview 1

Additional context

It seems inconsistent. Occasionally I get 10 calls on each api call, but most runs the final API only runs 9 times.

$ PORT=8085 pewpew run ProviderEndsEarly.yaml
Starting load test. Test will end around 10:15:32 28-Oct-2020 in approximately 5 minutes

Bucket Summary 10:10:00 to 10:11:00 28-Oct-2020

- GET http://localhost:8085?count=*:
  calls made: 10
  status counts: {204: 10}
  p50: 0.741ms, p90: 1.439ms, p95: 330.495ms, p99: 330.495ms, p99.9: 330.495ms
  min: 0.459ms, max: 330.495ms, avg: 33.744ms, std. dev: 98.875ms

- GET http://localhost:8085?count=*:
  calls made: 10
  status counts: {204: 10}
  p50: 0.878ms, p90: 1.492ms, p95: 2.133ms, p99: 2.133ms, p99.9: 2.133ms
  min: 0.662ms, max: 2.133ms, avg: 1.051ms, std. dev: 0.413ms

- GET http://localhost:8085?count=*:
  calls made: 9
  status counts: {204: 9}
  p50: 0.877ms, p90: 1.349ms, p95: 1.349ms, p99: 1.349ms, p99.9: 1.349ms
  min: 0.686ms, max: 1.349ms, avg: 0.904ms, std. dev: 0.197ms

Test will end around 10:10:42 28-Oct-2020 in approximately 0 seconds

Test Summary 10:10:32 to 10:15:32 28-Oct-2020

- GET http://localhost:8085?count=*:
  calls made: 10
  status counts: {204: 10}
  p50: 0.741ms, p90: 1.439ms, p95: 330.495ms, p99: 330.495ms, p99.9: 330.495ms
  min: 0.459ms, max: 330.495ms, avg: 33.744ms, std. dev: 98.875ms

- GET http://localhost:8085?count=*:
  calls made: 10
  status counts: {204: 10}
  p50: 0.878ms, p90: 1.492ms, p95: 2.133ms, p99: 2.133ms, p99.9: 2.133ms
  min: 0.662ms, max: 2.133ms, avg: 1.051ms, std. dev: 0.413ms

- GET http://localhost:8085?count=*:
  calls made: 9
  status counts: {204: 9}
  p50: 0.877ms, p90: 1.349ms, p95: 1.349ms, p99: 1.349ms, p99.9: 1.349ms
  min: 0.686ms, max: 1.349ms, avg: 0.904ms, std. dev: 0.197ms