Flag to disable the syntactic context in error messages

Motivation

In many development environments, the source span is the primary means of seeing what an error message relates to, and the In the expression: and In an equation for: clauses are not particularly relevant. However, they can grow to be quite long, which can make the message itself both feel overwhelming and interact badly with limited-space areas.

Proposal

I propose that there be a flag to disable the showing of the syntactic context.