The following try jobs ended in exception 

https://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_variable_chrome/builds/10/
https://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_variable_chrome/builds/11/
Traceback (most recent call last):
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/run.py", line 397, in run
    recipe_result = recipe_script.run(api, api._engine.properties)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/loader.py", line 57, in run
    self.RunSteps, properties, self.PROPERTIES, api=api)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/loader.py", line 512, in invoke_with_properties
    **additional_args)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/loader.py", line 473, in _invoke_with_properties
    return callable_obj(*props, **additional_args)
  File "/b/build/scripts/slave/recipes/findit/chromium/compile.py", line 245, in RunSteps
    'report', [json.dumps(report, indent=2)], as_log='report')
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/recipe_api.py", line 220, in _inner
    return func(*a, **kw)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_modules/python/api.py", line 52, in succeeding_step
    return self.result_step(name, text, 0, as_log=as_log)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/recipe_api.py", line 220, in _inner
    return func(*a, **kw)
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_modules/python/api.py", line 46, in result_step
    self.m.step.active_result.presentation.logs[as_log] = text
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_modules/step/api.py", line 63, in active_result
    return self._engine.previous_step_result
  File "/b/build/scripts/slave/.recipe_deps/recipe_engine/recipe_engine/run.py", line 316, in previous_step_result
    return self._step_stack[-1].step_result
IndexError: list index out of range

It seems when writing the report it was passed incorrectly or had an unexpected format, causing subsequent steps to fail