Runtime and parsing errors carry an empty message

[cesarParra]

Every runtime failure surfaces as the string Runtime Error: with nothing after it.

Repro

Any of these:

try {
    expression.Evaluator.run('SUM([1, null, 3])', someId);
} catch (Exception e) {
    System.debug(e.getMessage());   // => "Runtime Error: "
}

expression.Evaluator.run('MIN([DATE(2026,1,1), DATE(2026,2,1)])', someId);  // "Runtime Error: "
expression.Evaluator.run('Contacts -> MAP(Cases)', accountId);              // "Runtime Error: "
expression.Evaluator.run('FORMATCURRENCY(100)', someId);                    // "Runtime Error: "

Expected: something naming what failed — the function, the argument, or "no such function".
Actual: Runtime Error: and an empty detail, for every distinct cause.

Notably, a function that does not exist at all and a function that exists but got a bad argument
produce byte-identical messages, so there is no way to tell "I typed the wrong name" from "this
function does not handle this type".

Parse failures are the same shape: Parsing Error: with nothing after it.

Why it matters

Working out why a formula fails currently means bisecting it by hand, one sub-expression at a time.
For an end user editing a formula in a UI there is nothing actionable to show them at all — the
message cannot be surfaced, because it says nothing.

Some errors do carry detail — the SOQL layer's "Didn't understand relationship 'x' in FROM part
of query call" comes through intact — so the machinery exists and it is specifically the
evaluator's own errors that arrive empty.

Environment

Expression 1.52.0.1, Developer Edition scratch org.