Fix divide by zero error

[Reidmcc]

Fix the divide by zero error from #5

Added a conditional to check that both relevant numbers are >0. This should exclude cases where no valid number exists as well. I think this would need to be done for all UpdateWithOps funcs across strategy plugins.

[nikhilsaraf]

wanted to acknowledge this PR, will look at it soon.

[Reidmcc]

Cool, thanks.

[nikhilsaraf]

style suggestion, otherwise it looks good.

[nikhilsaraf]

the code convention is to return errors when they are encountered rather than to wrap the real logic in deeply nested if blocks (you can imagine how deep this can get if you have a series of error checks).

instead of using the pattern:

    if (condition) {
        // do something
    } else {
        // log error
    }

can you use this pattern:

    if targetPrice.AsFloat() == 0 {
        return nil, nil, fmt.Errorf("targetPrice is 0")
    }
    if targetAmount.AsFloat() == 0 {
        return nil, nil, fmt.Errorf("targetAmount is 0")
    }
    // rest of the code stays here

note that in the suggestion above we're returning an error rather than handling it by logging. the caller should handle any errors that arise from this method.

[Reidmcc]

Changes made. Once we have this finalized and committed I'll check the rest of the UpdateWithOps funcs.

[nikhilsaraf]

lgtm, thanks!