db-seed-i18n.py can miss strings

db-seed-i18n.py can crash with an error like this:

  Error in oils_i18n_gettext line 16655 of SQL source file: Cannot parse the source. Empty strings in there?

When this happens, any potential strings after the line in question are not included in the POT file.

This ultimately stems from it not recognizing patterns like this, where the commas between columns are used before the strings, not afterwards:

    ,oils_i18n_gettext(
         'webstaff.cat.label.font.family'
        ,'Item Print Label Font Family'
        ,'coust'
        ,'label'
    )

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