Comment 2 for bug 1827000

TITLE: Upgrade from 18.10 produces warning from statistics.php

BUG SUMMARY: When upgrading from 18.10.0_RELEASE, a warning was produced:

[WAR] 50 (lib/statistics.php:2408) count(): Parameter must be an array or an object that implements Countable

It is possibly an error with group_type_graph function.

version: 18.10.0 > upgrading
database: MySQL
browser: Firefox

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Commit hash: 486fad78c9e774e0bbb0d66882cc4cf60716d214
Environment tested: Master
Browser tested: Chrome | Firefox
Theme used: Raw

PRECONDITIONS:
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1) User is on version: 18.10.0 and upgrades site to 19.04.0_RELEASE
2) User database is: MySQL
3) User browser: Firefox | Chrome
4) User is using php version: 7.2.18
5) fresh database (only admin user)

TEST STEPS:
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1) Log in as admin user
2) Browse to Reports (Administration menu > Reports)
3) Configure the report as follows and submit
     a) Institutions = All institutions
     b) Report type = Content

EXPECTED RESULT: Expected to see a time period and Wording of "No statistics available"

ACTUAL RESULT: I am seeing an error messagebas follows and Mahara: Site unavailable "A nonrecoverable error occurred. This probably means you have encountered a bug in the system" see attached screenshot of error message git

NOTE: I could not trigger the original error message - most configurations returned a time period and Wording of "No statistics available" or minimal data. Report type = Content was the only thing that triggered error.