Fix typos in ModelChain error messages

[RDaxini]

• Closes Typo in error message #2490
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[RDaxini]

Aside: changing the error messages did not fail the tests. Are we missing some test coverage here, or is this okay?

[cwhanse]

Aside: changing the error messages did not fail the tests. Are we missing some test coverage here, or is this okay?

For get_orientation the test doesn't check the text of the error message. Optional to add that.

For infer_aoi_model the test only checks the first part of the message string. I think this is OK.

[RDaxini]

For get_orientation the test doesn't check the text of the error message. Optional to add that.

For infer_aoi_model the test only checks the first part of the message string. I think this is OK.

Makes sense. Unless anyone objects, I'll open a PR later to add a quick test for the get_orientation error message.

[kandersolar]

Thanks @RDaxini