When reporting "conflicting or redundant options" errors, try to
ensure that errposition() is used, to help the user identify the
offending option.
Formerly, errposition() was invoked in less than 60% of cases. This
patch raises that to over 90%, but there remain a few places where the
ParseState is not readily available. Using errdetail() might improve
the error in such cases, but that is left as a task for the future.
Additionally, since this error is thrown from over 100 places in the
codebase, introduce a dedicated function to throw it, reducing code
duplication.
Extracted from a slightly larger patch by Vignesh C. Reviewed by
Bharath Rupireddy, Alvaro Herrera, Dilip Kumar, Hou Zhijie, Peter
Smith, Daniel Gustafsson, Julien Rouhaud and me.
Discussion: https://postgr.es/m/CALDaNm33FFSS5tVyvmkoK2cCMuDVxcui=gFrjti9ROfynqSAGA@mail.gmail.com
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