So multiplication by an ERR is not an error (from what I understand from quickly reading the ref).
``` 3 * ERR yields ERR 3 * U yields U (3 times undefined yields an undefined value) ```
The mathematical truth tables are in the appendix of the reference manual.
It is quite useful in a language to have a universal bottom value (undefined) and a universal top value (error). The key point is to avoid undefined behavior
(I'm not necessarily sure I like the trade-off you've chosen here, but I think the viscerally negative responses people are having are because of that, rather than thinking through the trade-off on its own merits)
For symmetry reasons, the error and undefined values work across all types, which cleans up one of the messes in JS, where you have undefined, NaN, null, and goodness knows what else. That we have a uniform error value for nodes is a very minor point; it is almost impossible to generate an error value in the protected arithmetic world of Beads. Square root of -1 is one of the only ways I can think of.
There is no try/except in Beads, there are no exceptions as all functions are total, and all arithmetic closed (like Excel).