Friendlier error message for invalid indices

[copumpkin]

For example, I got:

RUNTIME ERROR: Array index must be number, got string.

It would be easier to track down what was wrong if it told me what unexpected string it got

[sparkprime]

I agree, but out of interest was the line/column accurate?

[copumpkin]

Argh, I lost the original error and can't remember what caused it now. Will comment again if I run into it again.

[copumpkin]

Aha, I got it again, and the location was correct but a little confusing because I was looking for an array index. The actual culprit was (equivalent to):

local foo = [1,2,3];
foo.hello

It presumably happens because the dot notation gets desugared into square brackets, which mean that we end up with foo["hello"].

[sparkprime]

It'd be good for it to remember the fact that this started off life as a ".foo" and print a different error message in that case. However what you originally proposed is simpler and probably good enough.