Describe the Enhancement

A met-help question revealed that having the -type option for gen_vx_mask as an optional argument with "poly" as the default value causes some confusion. Changing -type from an optional to a required argument would be more clear:
https://rt.rap.ucar.edu/rt/Ticket/Display.html?id=99861

This task is to:

• Change -type from optional to required.
• Make sure the resulting error message is clear.
• Update existing unit tests and add the -type option to them, as needed.
• Update the documentation to indicate this change.
• Coordinate with METplus to make sure all the existing use cases still run after this change.

Time Estimate

1 day

Sub-Issues

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Relevant Deadlines

None

Funding Source

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Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy
  Should be no impacts, but as noted above, be sure to test that this change doesn't break any of the METplus use cases.

Enhancement Checklist

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