Decide on the convention for error messages

[sbarzowski]

For example:

RUNTIME ERROR: couldn't open import "no chance a file with this name exists": no match locally or in the Jsonnet library paths

vs

RUNTIME ERROR: Couldn't open import "no chance a file with this name exists": no match locally or in the Jsonnet library paths.

We need to decide how we want it and keep it consistent. It may require changing APIs slightly, so that errors from Go (file not found, etc.) won't break our convention and that golint is happy.

[ghostsquad]

is the only difference here the use of Capital letter in the beginning (C vs c), and the trailing period (.)?

[sbarzowski]

In the example, yes. I imagine the convention would cover more than that, e.g. how verbose it should be, whether to use "$Failure: $Reason" pattern or something else, how the errors for wrong type should look like, how to refer to arguments (3rd parameter of function foo, vs parameter bar) etc.

We can start small with the rules which are the most obvious and uncontroversial, like keeping consistent capitalization.