Duplicate error reason for request parameter when it is required

[NickUfer]

When I define a request parameter which is required I get the message value is required but missing twice when I call openapi3filter.RequestError.Error().

Schema:

#...
parameters:
  - name: 'hostname'
    in: query
    description: '...'
    schema:
      type: string
    required: true
#...

Code for validation:

if err := openapi3filter.ValidateRequest(c.Request.Context(), requestValidationInput); err != nil {
	c.String(400, err.Error())
	c.Abort()
	return
}

Message when the parameter is missing:
parameter "hostname" in query has an error: value is required but missing: value is required but missing