Friendly error when missing GitHub data provider

[alexangas]

Fixes #1251.

• [x] Did you write/update appropriate tests
• [ ] Release notes updated (if appropriate)
• [ ] Appropriate logging output
• [x] Issue linked
• [ ] Docs updated (or issue created)
• [ ] New package licenses are added to ThirdPartyNotices.txt (if applicable)

[github-actions[bot]]

Unit Test Results

854 tests   854 ✅  20s ⏱️   1 suites    0 💤   1 files      0 ❌

Results for commit 978d5513.

:recycle: This comment has been updated with latest results.

[github-actions[bot]]

Package	Line Rate	Branch Rate	Complexity	Health
gei	81%	72%	592	✔
ado2gh	84%	78%	631	✔
Octoshift	87%	76%	1345	✔
bbs2gh	79%	74%	692	✔
Summary	84% (7178 / 8565)	75% (1658 / 2208)	3260	✔