Fixes missing tissue error reporting

[lparsons]

Resolves #951

Summary Change Description

Use the correct rownum variable to report which row a missing tissue record is on.

Also, update the rownum+2 to be rownum+1 which seems to report the correct row number.

See affected issue(s).

Affected Issues/Pull Requests

• Resolves #951

  See comments in-line.

  Checklist

  This pull request will be merged once the following requirements are met. The author and/or reviewers should uncheck any unmet requirements:

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  • Associated issue/pull request requirements:
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